Absurd Beaks and Materials Engineers

My principal question was this:  When a toucan tries to fly, why doesn’t he end up planted in the ground like a lawn dart?

And when I thought slightly more seriously about this, I realized that I had several other questions about the toucan as well.  How did that beak happen?  Why would such a thing evolve and what is it for?  If it doesn’t pull him straight toward the ground at thirty-two feet per second squared, how does that engineering work?  It clearly has enough strength to take the beating any beak has to take.  It must weigh something.

As children, toucans were probably among the first five or so birds we all learned the names of, but I was realizing that I know almost nothing about them.  So I am setting out to change that.  Who are these beautiful birds with the absurd beaks?

And there is another reason I’m writing this, and it has to do with the fact that I’m a birder.  I’m not a great birder, but I am a birder, and birders are an odd lot.  I’ll tell you something about us:  There is a handful of birds out there which are so iconic that any birder will simply never forget his first sighting.  I remember my first bald eagle (Alaska, 1984), my first peregrine falcon (kayaking off Big Sur, 1991) (I got so excited I almost capsized and drowned), and my first flamingo (Celestun, Mexico, 2007).

And Susan and I both saw our first toucan in November of 2007 in a jungle fifteen miles southwest of where I’m sitting right now, and here’s the personal connection:  Early next month we’ll be moving to that jungle.  That very spot.  We were looking at property at the time, and now we’re buying it.  Five acres, with an off-grid home.  Toucans will be a regular part of our lives.

It’s time to learn something about them.

 

*          *          *          *

 

tuca,n topaz1
Keel billed toucan (Ramphastos sulfuratus) on a neighbor’s property.
Photo by Jim Fossheim.

The argument about what the beak is for has been going on for about a century and a half, and it’s showing few signs of resolution.  The first theory came from The Man himself:  Charles Darwin was convinced that the toucan’s beak was for a sexual display.  That’s been discredited, but I can see why he went there.  Most absurd things you see in nature are about sex.  (Most absurd things you see in the human race are too, but that’s off-topic for a Ranger Randy article.)  It’s a known phenomenon, and it even has a name:  It’s called sexual selection.  That’s what they call it when a trait evolves which contributes absolutely no survival value, but does help the organism attract a mate and reproduce more successfully.  The example they always use is the tail of the male peacock.  But the problem with the toucan’s beak is that both sexes have one, and they’re identical.  That almost never happens in courtship display adaptations, especially in birds.  Almost always, it’s only the male who gets weird.  The female tends to stay subdued in appearance and practical in design, because she has an actual job to do—she has to bear those children and raise them, and she may or may not be a species lucky enough to get any help in that from the male.

The next theory I ran into was that they have those outrageous beaks because they eat fruit.  Well, okay, they are fruit eaters (frugivores) but the problem I have with that theory is that the forest is just full of fruit-eating birds who have perfectly ordinary-looking beaks.  Orioles come to mind.

Hooded_oriole_(9154173510)
Hooded Oriole (Icterus cucullatus)
By U.S. Fish and Wildlife Service Headquarters
[CC BY 2.0], via Wikimedia Commons

It was suggested on the National Geographic website that the beaks allow them to reach fruit farther away from themselves on branches that wouldn’t support their weight.  Sorry, I’m not convinced by that one.

Another suggestion was that by reaching farther away for fruit without having to move, they are conserving energy, and improving their calorie mathematics.  That one didn’t sell me either.

Some have suggested that the beak intimidates predators and competitors.  Well, if so, it’s all show, because the beak is not strong enough to be used as a weapon, and toucans don’t fight with them.

It’s been proposed that they can reach farther into tree cavities for food.  It’s been proposed that it helps them plunder hanging nests (they can be egg-stealers).

And the scientific community was all abuzz in 2009 because Glenn Tattersall of Canada’s Brock University did a very interesting study and proved that the beaks are used for heat exchange.  They are well-supplied with blood, they are not insulated by feathers, and the toucan can regulate the blood flow to radiate away more or less heat and regulate his body temperature.  A wave of exuberant articles hit the popular press.  The British paper The Independent crowed, “Mystery of the Toucan’s Beak Solved.”

Well, I beg to differ, and so does the author of that study.  There is a difference between what an adaptation is currently used for, and why it evolved.  If you actually read the paper in Science Magazine, Tattersall himself says that the evolutionary forces that led to the beak “remain elusive.”  That said, it was a wonderful and important study, and he did conclusively prove, in an ingenious way, that they thermoregulate with their beaks.  (This is what jackrabbits’ ears are for also—they have nothing to do with hearing.)  But it could easily be what scientists call an exaptation—something that evolved for one purpose and then, down the line, got used for another.  A perfect example of an exaptation is bird feathers.  They originally evolved for insulation, and only later were adapted for flight.

Now, I want you to bear in mind that I’m an amateur naturalist.  My estimation of this situation is not going to stop very many great minds in their tracks.  But for what it’s worth:  I don’t think we’ve figured this one out yet.

As you probably guessed, the beaks are very lightweight.  That’s why there’s no lawn dart phenomenon.  The inside of those beaks is a three-dimensional matrix of tiny little struts, a sort of latticework, but in 3-D.  (The insides of our bones look like this too.)  The result is that although the beak is a third of his body length and up to fifty percent of his surface area (which is why it’s a great radiator), it is only a twentieth of the bird’s mass.

But in the case of the toucan, evolution has added another innovation to this design which has the engineering community all abuzz.  A materials scientist and aerospace engineer named Marc Meyers, at University of California, San Diego, looked into the design of the toucan’s beak, and found that as well as having that 3-D matrix of little struts, which are pretty common in the animal world (they’re called traberculae), there are also membranes spanning each space created by them, like little drum skins.  It is as if the whole structure had been dipped in a soapy liquid and allowed to dry.  This adds another whole dimension to the strength of that beak, because now what you have is struts carrying compression loads, and membranes carrying tensile loads, and if you’re not familiar with those terms, they’re pretty much what they sound like.  (I know them because Susan hung out with a lot of architects for most of her career.)  Compression strength means it resists being compressed.  Tensile strength means it resists being pulled apart.  A rope has high tensile strength and zero compression strength.  A stack of bricks is just the opposite.  The toucan’s beak has both.  But it gets even better, because there’s a third effect as well:  The cells created by the membranes are airtight, so there is also cushioning from air pressure, like closed-cell foam rubber.  It’s looking like this design is unique in the bird world, and Meyers is advocating getting some technology-imitating-nature stuff going on this, because he is really impressed with the strength-to-weight ratio of these beaks, and also with the complexity of the ways it absorbs force and resists damage.  He thinks there could be lots of applications for it.

toucan2
Gregarious, social and playful: A family of keel-billed toucans traverse the canopy.
Photo by Jim Fossheim

The toucan we see most often around here is the keel billed toucan (Ramphastos sulfuratus), and it’s been delightful to learn a few things about them.  They’re very gregarious, very social and very playful, and they enjoy tossing things back and forth to each other (they’re quite dextrous with those beaks).  One of their courtship rituals is a fruit toss, in which male and female flip morsels of fruit into one anothers’ mouths.  They travel around in small family groups of six or twelve, and they’re actually not the greatest flyers.  They’re a deep forest bird, with stubby wings, and they prefer hopping to flying.

Hopping, however, is something they’re very good at, and since they stay mostly in the upper canopy, which is very contiguous in a tropical forest, they can roam a long way just by boinging from branch to branch.  They nest colonially in tree cavities, and that cracks me up.  It seems like every time I write an article, at some point I come across something that makes me laugh, and this time that’s what it was.  Think about this:  Space is tight in your basic tree cavity, and they’ve got those humongous beaks.  So they have a trick when they settle down at night, in which they tuck their beak completely under themselves, and wrap their tail, which is basically double-jointed, forward over it, and become a little ball of feathers.

The young take eight to nine weeks to fledge (grow up), which is longer than most, and the main reason for the delay is that is that they have to grow that beak.  They’re not born with it.  It would never fit in an egg.

And yes, the female does get help from the male in child-rearing.

And I’ll leave you with one more important fact:  According to the expert breeders at Emerald Forest Bird Gardens in California, toucans hate sugary breakfast cereal.  Never touch the stuff.

Now you know.

 

 

 

By |2017-05-24T00:03:05-05:00October 20th, 2014|Nature Essays|4 Comments
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A Well-Defended Tree

On the path that runs from Dave and Nancy’s back porch to the Yal Ku Lagoon there is a small, unassuming acacia tree.  I’ve brushed past it hundreds of times.  It is a perfectly ordinary looking acacia tree—pleasant to look at, shades the trail nicely, lovely when it blooms—but man, you’d better be nice to it, because it is the most well-defended tree on the property.  In fact, it is defended by an army.  An army of ants.

I love symbiotic relationships.  If there’s anything that fills me with wonder more than organisms do, it’s the relationships between them.  And this one will blow you away, I promise.

The acacia is Vachellia collinsii, commonly called the swollen-thorn acacia, or the hollow-thorn acacia, and those thorns are so wicked that one punctured my truck tire once.  The thorns are hollowed out and occupied by one of a couple of species of ants.  The ants are in the genus Pseudomyrmex, and I tried to figure out which species we have back there, but they’re too little and too mean and I gave up.

AcaciaAnts
Ants patrol Dave and Nancy’s acacia. The beltian bodies are visible on the leaf tips.
Photo by Randy Fry

They nest and raise their larvae in the hollow thorns, but providing shelter is not all this tree does for them.  It also feeds them.  In fact, it feeds them carefully and generously, and with a diet tailored to their needs.  There are little nubs at the bases of the leaves called extrafloral nectaries which exude a sweet nectar and keep the adult ants well fed, but then at the tips of the new leaves there are also little pods called beltian bodies which are rich in protein, and the ants nip those off and feed them to their larvae.

AcaciaTire
My truck tire impaled by an acacia thorn
Photo by Randy Fry

What does the tree get out of it?  Well, let me put it this way:  You are looking at a tree that never has to worry about herbivore attack.  And if you’re a gardener you’ll know what a game-changer that is.  Just about every other plant in the world is plagued by insects from aphids to grasshoppers to mites to worms to caterpillars, not to mention the larger herbivores like mammals and reptiles…yet here this acacia tree serenely stands—in the middle of a tropical forest where the insect life is grandiose in its proportions—and it’s completely unscathed.  It has even stopped producing the chemical defenses against herbivore attack that other acacias use (alkaloids and cyanogenic glycosides), and it does not even have to toughen its growing leaf tips like other plants do, with the result that it can grow a lot faster and out-compete its neighbors.

The ants attack leaves as well as herbivores.  Any leaf of a different species that touches an acacia leaf gets quickly clipped away.  The acacia tree looks like it’s nestled in comfortably against its neighbors, but if you look closer you’ll notice that not a single leaf of a neighboring tree is actually touching an acacia frond anywhere.  Often the ants even keep the ground clear around the trunk of the tree.  I’m not making this up.  There are signs of it around Dave and Nancy’s tree.  They weed around it, preventing any other plants from getting established and competing for the water and nutrients.  This acacia lives a charmed life.  It doesn’t have a thing to worry about, not even competition.  This acacia lives in a patrolled, gated community.  Nothing goes on in that tree without the permission of the ants.  All the tree has to do is sit there and grow.

AcaciaWeeding
It is probably the ants who are keeping this area clear of weeds
Photo by Randy Fry

What’s interesting, though, is that the ants do not attack absolutely everybody.  I had this article half-written when Susan and I went walking around the Coba ruins yesterday and saw a wasp nest in a hollow-thorn acacia.  We looked at each other and blinked.  “Huh?” we said in unison.  We checked for the ants.  They were there alright.  We walked on, and saw a few more wasp nests in a few other acacias.  This was not random chance.  It was a preference.  I came home and did some more digging.  The wasps paint the touch points with a chemical that deters the ants and keeps them out of the nest.  The wasps like it because they are protected from predators by both the thorns and the ants.  (Yeah, I know, it sounds like an unpleasant bit of foraging to me, but there are animals who will tear up a wasp nest to get the grubs.)

Birds also build nests in hollow-thorn acacias, and love it there for all the same reasons the wasps do, but it is “not yet clear” why the birds do not get attacked.

AcaciaWaspNest
A wasp nest in an acacia at the Coba ruins
Photo by Susan Fry

One reason for this “not yet clear” stuff is that hollow thorn acacias have not been well-studied historically. First of all, I can attest that those ants do not like naturalists any better than they like herbivores.  But also, back in the day, botanists did all their field work with plant presses, and those thorns can really screw up a good plant press, and on top of that you end up with a plant press full of extremely vindictive ants.  They’re not the most pleasant trees to study, and I’m looking forward to moving on to my next article.

There are a few downsides to this system, though.  The acacia gets pollinated by bees, and the bees must avoid the ants, though they seem to manage it okay.  Also, the acacias do not colonize new areas well, because both tree and ants have to move together.  This is, after all, almost a full, two-way symbiosis (it’s called an obligate symbiosis).  The ants cannot survive at all without a host acacia, and as for the acacia, well, it does not survive well without the ants, because it has no other defense against herbivores.  An acacia seedling in a new area must wait about nine months before it can hope to get befriended by an ant colony, so it gets hammered and weakened by the bugs, and then, without its army of tree pruners, it gets covered over and shaded out pretty quickly.  That’s why it reproduces mostly via suckers from its roots, where it can immediately benefit from the neighboring ant colony.  An ant colony can span several trees, because they have multiple queens, making them what computer programmers call “scaleable.”

They did some studies on ant-acacia partnerships in Africa and discovered that if you fence off the acacia to protect it from large herbivores, it scales back its production of nectaries and thorns because it no longer needs the services of the ants.  I kid you not.  It lays them off.  But it sort of backfires, because then the ants have to find another way to make a living, so they go back to farming aphids like their ancestors did, and end up not only allowing these plant-eating aphids in the tree, but promoting and protecting them.

AcaciaSpider
Bagheera kiplingi
Photo by Randy Fry

Here in Central America there is one creature who has learned to game the system.  He’s a small spider, and he’s kind of cute (for a spider).  He’s called Bagheera kiplingi, and if you’ve read some Kipling you’re probably chuckling right now.  Yes, he was named after the lithe and agile black panther Bagheera in Kipling’s Jungle Book stories, because he’s a member of a family of lithe and agile spiders called jumping spiders (family Salticidae).  But he was named back in the late 1800’s and the scientist who named him had only a single dead specimen and no idea what it did for a living, so he missed out on one of the most entertaining ecological stories in spiderdom.  It wasn’t until 2001 that people from the University of Arizona started coming down to the Yucatan and studying this thing in situ, and here’s the scoop:  There are 43,678 species of spiders described by science, and this is the only one who is vegetarian.

He lives on the nectar from the extrafloral nectaries that are there for the ants.  And boy, do the ants hate that.  Those ants really want to kill him, but they can’t catch him because he’s a jumping spider.  He spends his whole life in that acacia tree surrounded by ants who want to kill him.  He brings to mind that iconic line delivered so masterfully by Jack Nicholson, playing a Marine Colonel in A Few Good Men.  I can almost see that Nicholson grimace as he says,  “I eat breakfast three hundred yards from four thousand Cubans who are trained to kill me.”  That’s what it’s like for Bagheera kiplingi, but they can’t lay their mandibles on him because he’s capable of amazing athletic feats.  He leaps from thorn to frond to thorn to avoid them, and he spends his down time on old, dried-up parts of the tree that are not patrolled.  But every now and then, when an ant is strolling by carrying a larvae, he’ll mug that sucker and steal the larvae and eat it.  It’s the only time he eats meat, and I think he only does it for retribution.

The jumping spiders in general are also a pretty good yarn, so I’m going to allow myself one of my tangents at this point.  There are about five thousand species of them, and the other 4,999 or so all use their athletic skills to ambush prey insects.  They are known for having excellent eyesight and high cognitive skills (for a spider).  They don’t use muscle contraction in their leaps, they use hydraulic pressure, which is why they don’t have gigantic hind legs like a grasshopper.  They have four pairs of eyes, giving them almost 360-degree vision, and the center pair (called the anterior median eyes) have a very narrow field of vision, but they have good depth perception.  If you’re an insect and he wants to jump you and eat you, he will turn the front of his body toward you to bring those anterior median eyes to bear, then he’ll round on you with the rear abdomen and legs, and then he’ll creep up, step by step, a lot like your house cat stalking a bird.  Finally, the last thing he does before the pounce is attach a strand of silk where he’s standing.  They call it a drag line.  If he misses or things get messy, he can climb back up to where he was, and it also helps him hold his position when he attacks something bigger than he is. But they can use it even more creatively than that.  Sometimes they will attach the drag line in a different location, so that it alters the trajectory of their leap.  They can even use this technique to nail an insect who is on an inverted surface.

Male_peacock_spider2.svg
Pretty, for a spider: A male peacock spider (Maratus volans) does a courtship display
By KDS444
[CC BY-SA 3.0], via Wikimedia Commons

They are known for traversing complicated routes to get in position for an attack, and sometimes the route even takes them out of sight of the prey for a period, which suggests that they have a pretty good memory on board.  They’ve been observed descending from one bush and climbing back up a neighboring one to get at a prey insect, and that kind of detour solving is just way more brain power than scientists can explain in a creature this size.

And man, you should see their courtship displays.  They rival the displays of peacocks and birds of paradise, with shimmering, iridescent blues, reds and yellows, and elaborate dances.  They’re really quite beautiful.

For a spider.

Now you know.

 

 

 

 

 

By |2017-05-24T00:03:05-05:00October 10th, 2014|Nature Essays|7 Comments
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A Beautiful and Devastating Fish

If I end up falling in love with the coral reef ecosystem, there’s a good chance I’ll get my heart broken.  It is so beautiful, so delicate, so complex, so exquisitely balanced—and under assault from so many directions.  There is overfishing, there is acidity from atmospheric carbon, there is sea temperature rise from global warming, there is sea level rise from global warming.  Developers mow down the mangrove forests that protect them from sediment runoff and they get buried.  Nitrate pollution from agricultural runoff and sewage causes algae growth that smothers them and takes all their oxygen.  And even ecotourism ain’t helping.

And now, as if they needed another problem, there are lionfish in the Caribbean.

Lionfish (Pterois volitans) are spectacular creatures.  They are beautiful, they are unusual, they are magnificently talented predators, armed with dramatic, arching, venomous spines—and they don’t belong in the Atlantic, they belong in the Pacific.

Mangroves

Mangrove forests protect the reef from sediment runoff
Photo courtesy of NOAA, public domain, via Wikimedia commons

Legend has it that lionfish got introduced into the Atlantic when Hurricane Andrew destroyed a public aquarium in Florida in 1992 and its six lionfish ended up in Biscayne Bay, but actually they had been sighted before then.  We can’t know, but probably it was thoughtless people giving up their aquarium hobby and tossing them into the ocean.  In the last decade, they have gathered their momentum, and their numbers and their range are both absolutely exploding.  The alarm you hear when you read up on it is frightening.  Environmentalists are scared.  The National Oceanic and Atmospheric Administration (NOAA) is scared.  Mark A. Hixton of Oregon State University says it  “could very well become the most disastrous marine invasion in history.”

They eat juvenile fish, and they’re very good at it.  And coral reefs are tremendously important nurseries for juvenile fish.  A lionfish can eat from twenty to thirty small fishes in just a half an hour.  A single lionfish can reduce the juvenile fish population in his area by 79% in just five weeks.  And there is a one-word answer to the question of why this threatens the entire reef and not just the fish population, and that word is balance.

I thought I’d seen some delicately-balanced ecosystems before I started reading up on coral reefs.  Man, I didn’t know what delicately-balanced was.  I’ll be writing more about coral reefs without a doubt, but one of the many hair-raising balancing acts that goes on out there every day is between the coral and the algae.  Algal encroachment is devastating to coral reefs, and the small fish are the herbivores who keep the algae grazed back.

In the Indo-Pacific oceans where lionfish come from, they have predators.  Groupers and several other fish will take them out, but the groupers on this side of the world don’t seem to know how to do it, and besides, we’ve overfished our groupers pretty badly.  Also, in their native waters, the prey fishes all know what a lionfish is, and they flee from it.  Some scientists think that one problem is that lionfish are so bizarre that no one around here knows what they’re looking at.  They look strange and they hunt strangely.  They herd fish into a corner with those pectoral spines and then nail them with a lightning strike.  They blow water across their prey to disorient it, they have specialized swim bladders that they use for side-to-side motion, and their stomachs can expand to thirty times their normal size, with the result that they can gulp down something two thirds their own length.  They’re outlandish, and the fish around here have never seen anything like them.  They don’t look like a predator to their prey, and they don’t look like prey to their predators, so they get to sashay around doing what they want and gobbling everything up.  Some divers are actually trying to train fish like sharks how to eat a lionfish, by feeding lionfish to them, but it hasn’t been real effective so far, and anyway, there’s argument about it.  A lot of folks make the reasonable point that it’s probably a bad idea to teach sharks to associate humans with food.

lionfish_at_Shaab_El_Erg_reef_(landscape_crop)

Outlandish: No one in the Atlantic knows what to make of a lionfish
By Alexander Vasenin CC BY-SA 3.0 via Wikimedia Commons

But if there’s a bit of good news to be gleaned, it’s this:  lionfish are very tasty.

There is a campaign underway in the environmental and diving communities here in Akumal to get lionfish onto restaurant menus.  There’s a small outdoor restaurant down the road from us that specializes in them, and the proprietress is an environmentalist, diver and lionfish hunter.   Akumal recently held its first lionfish derby, in which the diver to spear the most lionfish wins a prize, and chefs are ranged up and down the beach handing out samples of lionfish dishes.  Even NOAA has launched an Eat Lionfish campaign, and the folks at REEF.org have published a cookbook.  The FDA played the party pooper and pointed out that you risk ciguatera poisoning, and does not recommend eating lionfish.  Ciguatera poisoning is caused by a neurotoxin produced by a small dinoflagellate called Gambierdiscus toxicus which lives on the algae and coral of tropical reefs.  It gets grazed by the herbivores and magnifies up the food chain, so the large, top-level predators are the ones to avoid.  But other folks point out that it’s a risk you run when you eat any reef predator, including very common menu fish like grouper and snapper.  Susan and I walked down the street and tried some lionfish.  They’re delicious.
But, as you probably guessed, we’re stuck with lionfish now.  Opinion is unanimous that we will never eradicate them completely.  All we can do is try to keep their numbers pummeled down.  That’s why species introduction can be such a horrific act, and it’s why I’m such a native species bigot.  You can never un-introduce a species once it gets established.  Evolution just builds its organisms way too well for that.  The historical record is littered with environmental disasters caused by intentional or unintentional species introductions.  Someday I might compile an anthology of the more spectacular ones and publish it here.  For now, though, I think I’ll go for a swim and enjoy the haunting beauty of our reef—and then maybe walk over for a lionfish taco.
Now you know.
           
 
 
 

 

 
Copyright © 2014 Randy Fry

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By |2017-08-13T11:57:34-05:00September 5th, 2014|Nature Essays|3 Comments
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The Baddest Act In the Jungle

Let’s just put it this way:  Crocodiles are one of their prey species.

Jaguars are the baddest act in the jungle, and when there’s not an animal in your ecosystem who can take you down, it gives you personality issues.  Picture it:  You are the biggest cat in the Americas.  You are the third biggest cat in the world.  Those cougars and bobcats and lynxes in North America—they’re not even related to you.  You’re in the genus Panthera, thank you very much.  Your cousins are the lions of the African savanna and the tigers of Asia.  When that ancestor of yours crossed the Bering land bridge to the Americas back in the Pleistocene era (along with a gifted ape called Homo sapiens),  he was almost twice your size, and lived and fought in the megafauna world of mastodons and wooly mammoths, and God only knows what kind of predatory fights he got into, and actually the scientists don’t know either, but they generally call him  “Panthera genus, species unknown”, which means that maybe 13,000 years later, he had become you:  Panthera onca.  Terror of the jungle.  Apex predator in four different ecosystems.  Deity of the Maya.  The jaguar.

He’s in these forests.  Let’s talk.

*          *          *          *

Susan and I were lucky enough once to see a cougar (on a long night training run in Fort Ord), but it’s highly unlikely we’ll be fortunate enough to see a jaguar in our lifetimes.  They are even more reclusive than the cougar, and they favor dense jungle.  But you can hear them.  Our friend Victoria hears them at night behind her house outside Tulum.  They growl and roar, like lions, calling back and forth in the jungle.  And we know a hiking guide near Puerto Vallarta who came around a bend in the trial once and found himself facing one.  They stared at each other for most of a minute.  He said it was the most focused his mind has ever been.  Then the jaguar just turned and walked away.

But actually, in hindsight, our friend hadn’t been in any danger.  Jaguars bring to mind that iconic line from the film The Godfather:  If I wanted to kill you, you’d be dead.  They’re ambush predators, not chase predators.  They stay invisible to you until they are within a short charge or a single bound.  You don’t even know you have a problem until he’s airborne.  The rosettes on his coat are perfect for the dappled sunlight of deep forest, and even scientists who study big cats for a living say they’re remarkably skilled at this ambush-predator stuff.

jaguarPanthera_onca_at_the_Toronto_Zoo_2

A jaguar shows off the gape of his jaws
By MarcusObal [GFDL or CC BY-SA 3.0], via Wikimedia Commons

But once they hit a large animal, the way they close the deal is even more remarkable.  They not only are the biggest cat in the Americas, they also have the biggest and most powerful jaws, even proportionally.  Their bite carries two thousand pounds of force, more than any other cat, and the gape of their jaw is astonishing.  So when they jump a large prey animal, they do something no other cat can:  they drive their canines through the skull.  Usually right between the ears.  Death is instantaneous.  Neck-wringing is for sissies.

It is thought that this technique evolved because eleven thousand years ago (give or take a couple) there was an event called the Pleistocene Extinctions, in which we lost thirty-three of our forty-five genera of large mammals (those gifted apes I mentioned probably had a hand in this).  For a while there it got pretty hard to find a mammal, but there were lots of armored reptiles around, like turtles and crocodiles, and also giant armadillos—if you could get through their armor.

They do kill livestock, and they’re strong enough to carry a young cow up a tree.  One was observed dragging an 800-pound bull twenty-five feet across a pasture.  And when they kill a horse, what they will often do is leap on its back, put one great paw on the muzzle, one on the nape of the neck, and then twist, like an evil chiropractor, dislocating the neck.

They love water.  They like to be around rivers, they can catch fish in a pinch, and crocodile is one of their favorite foods.  They will kill a crocodile by exploding out of the water like a crocodile.  They can swim carrying a very large kill.  They are also completely at home in the trees, and they can hunt arboreally.  They can even make a go of it in habitats like arid grassland and seasonally flooded wetlands, but by far they prefer deep jungle.  It’s what they’re built for.  They’re not long-limbed and fleet-footed like their cousins on the savanna.  That doesn’t work in dense jungle.  They’re huge, but they’re compact—short-limbed and extremely muscular.

They are considered a keystone species.  A keystone species is one which has a disproportionate influence on the ecosystem.  It’s a reference to the keystone at the top of a stone arch.  It carries less weight than any other stone, but remove it and the arch collapses.  The jaguar is the apex predator.  Remove him, and you get an over-abundance of the next predator down, and then a cascading re-shaping of the whole food chain.

They used to be common in the United States.  Thomas Jefferson recorded their presence in 1799, and they were seen in California (Monterey is mentioned), as far north as Missouri and as far east as the Carolinas.  They quickly got exterminated by Anglo-Americans, and the ones in the Southwest were the last to go.  The last female jaguar was shot by a hunter in Arizona in 1963.  Arizona outlawed jaguar hunting in 1969, but with no females, there wasn’t much hope.  Over the next twenty-five years only two male jaguars were seen (and shot).  It seemed to be all over for the jaguar in the US.

Then, in 1993, an Arizona hunting guide named Warner Glenn was hunting in the Peloncillo Mountains when his dogs brought a large animal to bay on top of a rock.  It was a jaguar.  It changed his life.  On the spot, he became a jaguar conservationist and researcher.  He knew the mountains well, and he started planting webcams.  The sightings started coming in.  There were jaguars in the States again.

Glenn still hunts, but you don’t want to harm a jaguar around him, and don’t even get him started about that stupid border fence that fragments their habitat and blocks the migration of everything except human beings.  Warner Glenn belongs to a bygone breed—a hunter-conservationist, in the mold of Teddy Roosevelt.

Templo_de_los_guerreros

Jaguars adorn a temple in the Chichen Itza ruins, Yucatan Peninsula, Mexico
By Marco Soave [GFDL or CC BY-SA 3.0, via Wikimedia Commons

There is a jaguar god in every major Mesoamerican culture.  Carvings of them are all over the Maya ruins, shamans are thought to be able to change form into a jaguar, and only the royalty were allowed to wear jaguar pelts.  The Maya believed the jaguar was able to move between worlds, from physical to spiritual to the underworld.  This is probably because the jaguar can operate in so many realms, from aquatic to terrestrial to arboreal, and also because he can be active in day or night, and to the Maya, day and night are two different worlds.  The Olmecs, west of here, even had a supernatural character in their folklore that anthropologists call a were-jaguar, a shape-shifting, half-man, half-jaguar sort of guy,  who was believed to be the product of sex between a woman and a jaguar.  Maya kings would give themselves grandiose names incorporating the Maya word for jaguar (balam), so there were kings named Scroll Jaguar, Bird Jaguar, Moon Jaguar, and Jaguar Paw III.

The Maya created an instrument involving a drum, a string, a stick and a rasp, which sounds exactly like the growl of a jaguar (which is a frightening sound), and I mean they nailed it.  If you were walking through the woods and you heard this thing, you’d pee your pants.  This proved to me for the second time that the Maya had some serious acoustical skills.  (Read this post for another example.)   By the way, this might be the only stringed instrument that evolved in the Americas, but be careful who you say that to, because they’re still arguing.  The problem with stringed instruments is that they don’t survive well, so it’s pretty hard to know.  The reason we know about this one is that the Maya were a literate people, and carved all manner of text and images into their stone walls, including a bass-relief picture of a guy playing this thing.  An Ethnomusicologist named John Burkhalter was able to build one, and you can hear him play it below. You can hear the real animal here.

Jaguar numbers are dropping precipitously.  Their range has contracted at both the north and south ends, and they don’t handle habitat destruction and fragmentation well.  But also there’s hunting.  In the nineteen-sixties, 15,000 pelts per year were coming out of the Amazon Basin.  Also, they do kill a lot of cattle.  Someone did a study and the ranchers are not exaggerating this.  Most Latin American ranchers shoot them on sight, and a large operation will even have a full-time jaguar hunter on the payroll.

Which is a sad way to end a story about a magnificent animal, but hell, those are the times we live in.  I’m almost getting used to it.

Now you know.

By |2017-05-24T00:03:05-05:00August 21st, 2014|Nature Essays|Comments Off on The Baddest Act In the Jungle
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Jellyfish and Formula One Race Cars

When you get stung by a jellyfish, you’ve just been harpooned by a projectile that was fired with an acceleration of 5.4 million G’s.

Admit it, you didn’t know that.

For years, jellyfish have been one of my favorite mind-blowing organisms, but two things in the last two days prodded me to finally write an article about them.  One was our good friend Dave.  Dave lives on the shore of a beautiful Caribbean lagoon in Mexico (and so do we—we rent a casita from him), and he has noticed that lately there are a lot more jellyfish than usual in the lagoon.  He loves the lagoon and is always keeping an eye on it, and he is afraid something is amiss, so he asked me if I could look into it.  Then one day later Susan got an email from another dear friend of ours, Cathleen, back in Monterey, who tells us that millions of small surface jellyfish called velellas had washed up on the beach there in the last few days.

So okay, it’s time to do this thing.

Jellyfish (phylum Cnidaria) are as remarkable for what they are not as for what they are.  Listen to what your basic jellyfish does not have: He does not have a brain.  He does not have a heart or a circulatory system.  He does not have lungs or gills.  He does not have eyes.  He does not have a skeleton.  And he might be a she, because he does have a gender.

He only has a single muscle around the perimeter of the bell.  He only has a single orifice, called a mouth-anus, and a single gastro-intestinal organ behind it, which is stomach and intestine combined, and does all the digesting before he spits out the remains.  The closest thing he has to a nervous system is called a neural net, which can be pictured as a non-centralized web of neurons sort of draped over the bell.  When you poke him, each neuron fires to its neighbor, in an “I just felt something, pass it on!” sort of way, and somehow he ends up responding and pulsing away in the other direction.

IMG_0894_dnsz
Yal Ku Lagoon (the marine mammal is the author)
Photo © by Susan Fry

In fact, even what he does have, he does not have very much of, because he is 98% water, and that’s a very cute trick—only two percent of him is anything he has to find or pay for.  It’s a very cheap way to be an organism.  The Jell-o in your refrigerator is 90% water, so jellyfish have the process dialed in a lot better than the Kraft Foods corporation does.   As for us, we’re about 55 to 60 percent water, so we’re pretty high-maint.  It takes a lot of nutrients and expensive chemicals to make a human being.  (At today’s prices, you’re worth about $160.00.)

They’re able to pulse around, but that’s as much to draw prey into their tentacles (actually called oral arms) as anything else.  The reason they don’t have to obsess too much about locomotion is that they’re planktonic.  Most people don’t realize this, but you don’t have to be small to be plankton—it just means that you go where the currents do, and that’s what jellyfish do.  In all, jellyfish seem to have been designed by an engineer who was over-obsessed with the cheap-and-simple design model, and they seem merely fun, just a weird and amusing creature—until you get to the sub-cellular level.  That’s where jellyfish go from being amusing to being amazing.

So think about this for a moment:  You’re ninety-eight percent water.  Even a soft, pudgy human finger can poke right through you.  You’ve got no speed, no hardened exterior, no teeth or claws—and what do you decide to go around killing and eating for a living?  Bony fishes, fer God’s sake!  How do you subdue something like a fish, which has a skeleton, scales, fins, spines, teeth, thrashing muscles and an intense desire not to be killed?

With toxins, that’s how.  You poison them.  And now I want to talk about dish gloves.

When you get stung by a jellyfish, you have been harpooned by thousands of tiny projectiles on the ends of flexible hollow tubes, fired from cells called nematocysts.  The nematocysts cover the oral arms that hang down curtain-like from the bell, and the way those things fire is just amazing.  Picture taking a dish glove, and poking one finger of it inside-out into the glove.  Now put the opening of the glove over your mouth and blow into it.  The finger everts—it shoots outward until it’s fully extended and right-side-out again.  That’s how those nematocysts fire.  What’s absolutely brilliant about that design is that there is no drag.  None.  This thing is not travelling through the water, it is growing through the water.  Its surface is not moving at all relative to the water, so it can fire at tremendous speed, and without veering off due to turbulence.  Sticking with the dish glove analogy for one more moment, if that thing were the diameter of a dish glove finger, it would be the length of a football field.  And it fires all that distance through water, and in a straight line.

And with up to 5.4 million G’s of acceleration.  They’re still studying it, but that seems to be the upper estimate.  To give that number some meaning, you have to browse down a chart of sample G-force numbers, which is an extremely fun thing to do (okay, maybe I’m a little weird, but I call it a good time).  When the Space Shuttle takes off it never gets above three G’s.  The top recorded drag racer managed to hit 4.3.  Aerobatic planes can deliver 4.5 to 7 G’s.  Twenty-five G’s and up is a number that will usually kill you.  Your average bullet fires at 100 to 200 G’s.  It is thought that a guy named David Purley experienced the highest G load of any human being without dying.  He was a Formula One race car driver.  On one particularly bad day he went from 108 miles per hour to zero in twenty-six inches.  He actually was a very courageous guy—he once abandoned his own race to try to save a driver trapped under a burning car.  Later he went into aerobatic flying and died in a plane crash, but anyway, you don’t usually get into the thousands or millions of G’s until you’re talking about either sub-atomic particles in accelerators, or jellyfish.

DavidPurley
David Purley
Photo by Gillfoto CC BY-SA 3.0, via Wikimedia Commons

And would you like to know what force it is that instantly creates this tiny but incredible, millions-of-G’s explosion?  Osmosis, that’s what.

This blew me away (so to speak).  I had always thought of osmosis as a lazy, slow kind of a force that given time will equalize concentrations on opposite sides of a permeable membrane.  Not so—apparently it can be both very powerful, and very instantaneous.  The bulb or capsule (called a cnida) into which that dish glove finger is tucked is filled with a solution rich in suspended calcium, but it’s safely imprisoned behind waterproof walls.  What happens when the trigger is pulled got a little technical for me and changed from article to article, but if I understand it correctly, a change in electrical polarity causes a membrane to instantly go from impermeable to permeable, and suddenly all that calcium-rich fluid is exposed to surrounding normal fluids, and the osmotic reaction is absolutely explosive.  Water rushes into the bulb at lightning speed, briefly creating 140 atmospheres of pressure, and the nematocyst blows, in what one scientist calls “the most explosive envenomation process that is presently known to humans.”

The harpoon tip is also designed to rotate as it travels, like a bullet fired from a rifled barrel, and I’m assuming that that also helps to keep it straight.  And, of course, the whole tube (and bulb) is full of venom.  When it finally reaches its full length, which is usually after it’s thoroughly buried in your flesh, there is still pressure left in the bulb, so the harpoon tip blows off the end of it, and all that venom empties into your system.  Cute, no?

Nematocyst_discharge
Nematocyst Firing Sequence
By Spaully [CC SA 1.0 or Public domain], via Wikimedia Commons

The trigger that gets pulled is interesting too.  There are actually at least two.  One is mechanical and simply gets depressed by the prey like the trigger on a gun (called a mechanoreceptor).  But to keep these valuable nematocysts from firing on wharf pilings and other objects that cannot be eaten, there is also a chemosensor—basically an olfactory—which has to detect something organic like animal protein before the system will arm itself.  There are some species of box jellyfish (class Cubozoa) in Australian waters that are among the most venomous creatures in the world and can kill you outright, and have enough venom on board to kill sixty others like you, but the only thing you need to protect yourself from them is pantyhose.  That’s what the Aussie lifeguards used to wear before there was such a thing as a Lycra bodysuit.  The nematocysts are plenty long enough to fire through the fabric, but the chemosensor is a tiny thing and cannot reach through the fabric to detect skin, so nothing fires.

*          *          *          *

Well, I could keep going, believe me there’s more, but I should wrap up, and circle back around to what Cathleen and Dave have each been seeing.

Cathleen, those deep blue little surface jellyfish you’ve been seeing washed up in the millions on the beaches of Monterey are commonly called by-the-wind sailors, and their latin name is Velella velella, the only species of their genus.  They are cnidarians, but they’re pretty different from the typical jelly I’ve been describing here.  They’re more related to the Portugese man-of-war, and, like the man-of-war, they’re colonial—there’s more than one cnidarian at work there.  They’re an interesting animal.  They live entirely on the surface, floating on gas-filled chambers like a Zodiac raft, and with little transparent, leaf-shaped sails sticking up.  The velellas are longer than they are wide, and their sail sticks straight up, but it is mounted diagonally, set at forty degrees off the longitudinal axis of the creature.  This allows them to sail in a direction up to sixty-three degrees off the downwind direction, which is a level of control that pushes the limits of what we call planktonic.  Wind is usually light at this time of year, but when there is a weather anomaly and the wind gets stronger, millions of them will strand on beaches up and down North America (these things exist in all the world’s waters, and from sub-arctic to tropical latitudes).   Here’s the fun part:  When that happens, as it is now, and you’re looking at foot-thick windrows of decomposing velellas on the beach, you would think this has been an absolute disaster for the poor species, but there’s a catch.  Velellas have an isomorphic form, and half of them have sails that are angled forty degrees the other way.  I kid you not.  That half of the velella population is still out at sea right now having a good time.

Velella
Velella, aka By-the-wind Sailor
By Wilson44691 [CC0], via Wikimedia Commons

Dave, the question you ask is more complicated, and you, like Cathleen, are also looking at a delightfully non-typical jellyfish.  It is commonly called the upside-down jellyfish, or the mangrove jellyfish, but there are several species, so yesterday I took a dive and looked at one of them myself, and if I’ve ID’d it correctly it’s Cassiopea andromeda (there must have been an astronomer in the room with the taxonomists).  I remember there being a tank of these in an exhibit when I was a docent at the Monterey Bay Aquarium, and looking at them, lying there on the tank bottom, upside-down on their bells and pulsing with their oral arms waving in the water, and wondering, “Where in the hell did they find those things?”  Now they’re 200 feet from where I’m sitting.  They can pulse around like any other jellyfish, but then they’ll turn upside-down and settle on the floor of a shallow lagoon with their oral arms sticking up, looking for all the world like a sea anemone, which is also a cnidarian, just built upside-down.  (In fact, sometimes a sea anemone is a jellyfish, just in a different life stage, but that will have to wait for another article.)

They lie there like that because they are photosynthesizing.  They’ve taken a cue from the coral around them, and just like the coral they have a symbiotic relationship with a photosynthesizing algae called zooxanthellae, and it does most of the nourishing for the creature, though the jellyfish still kills and eats small plankton and other prey.

To get to your question, several things can cause a surge in jellyfish numbers, which is commonly referred to as a jellyfish bloom.  One is runoff.  Nitrates and other pollutants and nutrients, like sewage or agricultural runoff, cause something called eutrophication, in which the unusual flood of nutrients causes an intense algae bloom and the algae suck up all the oxygen, creating oxygen-poor “dead zones,” and jellyfish are much better able to handle low oxygen than the bony fishes with whom they compete for a lot of their food.  Jellyfish are more able to handle acidity in the ocean waters than other organisms (though no one is sure why).  Coastal and off-shore construction of things like pilings and drilling platforms create more attaching surfaces for jellyfish in their polyp, or anemone-like, stage.  Jellyfish reproduction is accelerated by warmer waters.  And because of the competition for prey between jellyfish and bony fish, pretty much anything bad you do to your fish populations will create more jellyfish.  Jellyfish also have a multi-stage reproductive cycle that includes some non-sexual cloning, so they have a fallback process that allows them to continue to reproduce while they wait for their numbers to rebound enough to find mates.  To understand the broad strokes of what’s going on, remember how simple jellyfish have kept themselves.  Animals like bony fishes, with high metabolisms, complex organs, and high oxygen and energy demands, simply find it hard to compete with jellyfish when things change, or times get tough.  In other words, when human beings start screwing with the planet.

MangroveJellyfish

Upside-down Jellyfish (Cassiopea andromeda)
Photo © Raimond Spekking, CC BY-SA 4.0 (via Wikimedia Commons)

There is huge argument right now about jellyfish blooms.  Some see an extremely scary global trend.  There is a jellyfish in the waters between Japan and China that measures six and seven feet across the bell and weighs 480 pounds, and its blooms have become annual.  One fishing trawler capsized itself trying to haul in its nets, and the crew had to be rescued.  People are blaming pollution from the Yellow River in China.  Last year, nuclear power plants in Scotland, Japan, Israel and Florida had to shut down due to jellyfish clogging the inlet pipes of the cooling system.   Ireland’s entire salmon farming industry got destroyed one year by jellyfish.  Desalination plants have also had to shut down.

But the problem is, all this shouting and arm-waving is anecdotal.  Booms and busts in nature happen all the time, and we actually know very little about jellyfish.  Jellyfish are notoriously hard to study.  You can’t tag one.  They blow into town and then blow out and nobody knows where they go.  Haul one onboard and you have a pile of slime.  Put them in any ordinary fish tank and they all end up piled in one corner, or sucked up against the filter inlet.  We don’t know jack scat (that’s a euphemism I just made up) about jellyfish, and we need to.  People have been quick to implicate global warming, but Steven Haddock of the Monterey Bay Aquarium Reseach Institute believes that there are many other possible causes that would come before that.  “It sounds to me like scary rhetoric to try to get funding,” he says.  Rob Condon of Dauphin Island Sea Lab in Alabama has been gathering data going back to the 1700’s, and believes that there is nothing suggesting a global catastrophe.  He points out that four thousand years ago in Crete, they were painting pictures on their pottery about jellyfish blooms.

So, like so many things I write about, we don’t really know.  And we need to.  But what haunts me about the overarching trajectory of this story is a fairly simple truth that is apparent to me no matter which papers I read or which way I turn them, and it goes something like this:   Anything bad we do to our fish populations, or our oceans in general, is likely to create jellyfish blooms.

I don’t have a good feeling about this.

Now you–

Well, no, I guess you don’t.

Copyright © 2014 Randy Fry

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By |2017-08-13T12:05:14-05:00August 4th, 2014|Nature Essays|8 Comments
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Anti-grav Geckos

“That’s really a pretty cute trick,” I said to myself.

What sort of surprised me was that I was saying anything to anyone at all, including myself.  Susan and I had just watched a World Cup soccer match in a thatched palapa bar here in Akumal, Mexico, then walked a mile and a half home, and if the heat was an unprovoked assault, the humidity was a crime against humanity.  With three margaritas in me and drenched in sweat, I burst into the bedroom and groped for the air conditioner like a poisoned man groping for the antidote, and then we both fell backwards onto the bed—and then this little gecko ran across the ceiling above my face.

GeckoOnCeilingCroppedDnsz
The gecko above our ceiling fan (Sorry, not the greatest shot)
Photo by Randy Fry

Between the gecko and my face whirled the scythe-like blades of a ceiling fan, in a sinister blur.  Losing her grip would have been a scene from a grade-B gecko gore movie, but she was nonchalantly confident, and scampered upside-down all the way across the painted concrete ceiling to the wall, then transitioned fluidly to the vertical surface, and disappeared into her hidey hole behind the valance of the window blind.  Okay, I said, still managing somehow to converse with myself.  I have to find out how they do that.

Just as soon as the temperature in here drops by twenty degrees.

Like most times I’ve ended up reading something astonishing, the reason I wanted to know more was that I already knew a little.  I knew that they do not do this with claws, they do not do it with suction cups, they do not do it with a goopy adhesive substance, and they are not affected by the smoothness or roughness of the surface.  What the hey?  I started reading.

gecko
A better shot of a house gecko
By Praveenp
[CC BY-SA 3.0], via Wikimedia Commons

If we’ve ID’d her correctly, she’s commonly called the house gecko (Hemidactylus frenatus), and I call her a she because she barks at night.  I kid you not.  It took us forever to figure out what that sound was.  It’s a female house gecko advertising for a mate.  But something Susan found out in her research is that she doesn’t need a mate.  The house gecko doesn’t, I mean.  The house gecko is parthenogenic, meaning that the female is capable of making babies without the help of a male.  That’s also a very cute trick, but actually she only does it in a pinch, because when you do that, genetic diversity suffers.  In case you don’t remember your high school Darwinian evolution, or in case they’re not teaching it anymore, sex is all about diversity.  Diversity is the only reason you have a sex life.  You don’t want all your kids to be carbon copies of yourself, because if your environment throws you a curve ball, you want some of your kids to be weirdos, because there’s a chance the weirdo might be able to handle the change.   Which is probably the only reason I’m on the planet.

Everyone around here loves having a gecko in their house, and we are blessed with either a couple of them, or with one who is very mobile, I haven’t figured out which yet.  The reason people love them is that they eat bugs, and the bugs down here in the tropics are, well, let’s just say the potential subject of several future Ranger Randy articles.  In Spanish, house geckos are called limpia casas—house cleaners.  They can eat a spider twice the size of their head, and I just love that about them.  For Susan’s part, she loves that they eat mosquitos.

They’re pretty small lizards.  They only get about as long as your finger, but they leave huge droppings, and Susan and I thought we had rats in the house, which are not a part of the natural wonderland we wanted to invite into our living space.  The property caretaker, Rene, had to convince us that they were gecko droppings.

Even this fascinated me.  Like any self-respecting naturalist, I like turds.  Okay, the field of study is actually called scatology, but I don’t mince words for my readers—we naturalists like turds.  There is a lot of information in their contents, and there is a lot of information in their abundance, location and distribution, and the really cool thing about them is that they don’t run, they don’t hide, and they don’t bite.  Turds are great sources of information, and there’s not a wildlife biologist anywhere who is at all shy about working with them.  And actually, I had already noticed that these had one white end, which means that you’re dealing with an animal who does not urinate.  The white is uric acid.   That usually means a bird or a reptile.  So I was easily convinced that we had geckos and not rats.  (But good heavens, the size of those things!  Ow!)

 

*          *          *          *

 

So now I’m remembering my father in one of our late-night debates (and we had a lot of them) and he’s saying, “We must remember that nature is not divided into disciplines the way universities are.” It was one of his favorite quotes, and what’s annoying me as I write this is that I can’t remember which famous scientist he attributed it to, and now, even with all the power of the Internet at my fingertips, I can’t for the life of me find it, so if anyone out there can source that quote, please email me, because I’m dying to remember.  Maybe an attribution doesn’t exist and it’s one of those quotes that came from no one in particular.  It doesn’t matter, they are profoundly wise words, and sure enough, when I looked into this anti-grav thing that geckos do, the biology of it took me straight into physics.

There is a very faint and feeble force in physics called the van der Waals force, and even if you are a scientist, it might not be a force you hear very much about.  It does hold molecules together, sort of, but it is not to be confused with the irrevocable force of a chemical bond, which results from something slam-clank solid like an electron shared between two positively charged nuclei, and is bomb-proof and almost impossible to break.  No, the van der Waals force is a ghost of a force compared to that.  I’m not really qualified to explain it to you, but it has to do with the charge fluctuations of molecules naturally falling into sync and creating a tiny attraction.  It is incredibly subtle, but it is the reason that if you get any two molecules in this universe close enough to each other, they will be slightly attracted to each other.  It is weak and easily disrupted and easily overpowered, but it is there, and if it were not there, you would not recognize this place.  Without the van der Waals force, water vapor would not condense into either liquid or ice.  Without it, there would be no crystalline structures—no snowflakes, no quartz.  It is the reason water has surface tension, and without it there would be no such thing as a droplet.  It is the reason we have melting points and boiling points, and it makes possible gigantic molecules like enzymes, and DNA.  Without the van der Waals force, life as we know it would not be possible, and it is the reason geckos stick to the ceiling.

We don’t feel the van der Waals force when we touch a wall because on the microscopic level so little of our body is actually in contact with it.  There is the shape of our hand, the roughness of our skin, the way the two shapes do not conform to each other.  Down there on the molecular level, very, very few person molecules are actually touching wall molecules.  That’s the problem the geckos solved.  So I’m going to take you on a zoom-in, a big one.  Hang onto you chair…

First of all, let’s zoom in on the bottoms of those cute little club-shaped toes that geckos have.  The bottoms of those toes are plated like the treads of a caterpillar tractor so that they can roll on and off of a surface incrementally and fluidly.  More on that in a bit.

gecko_scan
A gecko shows off her laminellae (Click to enlarge)
By ZooFari [CC BY-SA 3.0], via Wikimedia Commons

Zooming in on one of those plates (called laminellae), we find that it is covered with tiny hairs, and each hair is pretty short, but there are a ton of them—up to 1,400 per square millimeter.  Let’s zoom in more:

On the end of each single hair (called a settae) there are, I kid you not, up to 1,000 little pads called spatulae, and each one is only 200 nanometers wide.  Now, to give you an idea of where we are at this point in our zoom, a nanometer (nm) is a billionth of a meter.  So these structures with which our little gecko finally makes physical contact with the painted concrete of my ceiling are actually smaller than the wavelength of visible light.

The end result?  There is no part of any surface this gecko walks on that gets missed by this set-up.  She has maximized her surface area to an incredible extent.  She is playing touchy-feely with our ceiling at almost the molecular level.  That feeble little van der Waals force has become a rock-solid bond.  She has no fear.  She will never fall.

In fact, it works so well that she actually has adhesion to spare.  Evolution did have to over-build her a little bit.  After all, she lives a fairly complicated life, and as she moves around, not all those little structures are in contact with the wall all the time—in fact, not even all four of her feet are on the wall all the time.  So at any given moment, she’s only using a fraction of her adhesion capability.  But scientists love to run theoretical numbers.  They estimate that if you could set up an ideal situation and get every spatulae she owns on the ceiling at the same time, you could hang 293 pounds from that little lizard.

Which left her—or at any rate her ancestors—with an interesting problem that had to be solved as this thing evolved.  If you took your average appendage—say a human hand—and covered it with those spatulae and setae and slapped it on the wall, you’d never get it off.  You’d still be tugging at it.  And that’s why geckos’ feet have that unusual anatomy I mentioned.  Everything happens on those little tractor-tread plates, and her toes are double jointed—that is, the knuckles can bend backwards (it’s actually called digital hyperextension), so she is able to roll her toes off the wall.

When this van der Waal angle started to become apparent to researchers (only a decade or so ago), technology began to imitate nature.  A team at Simon Fraser University in British Columbia has built a robot inspired by the gecko.  Sure enough, it’s on tractor treads.  They have managed to create artificial setae out of a material called PDMS whose real name I don’t have room to type here, and this thing can climb walls wet or dry, smooth or rough.  They’ve already got the prototype working.  You can watch it below:

A team at Northwestern University in Evanston, Illinois is creating a tape called Geckel, which will work wet or dry, smooth or rough, and won’t wear out for a thousand or more uses.  They’re picturing medical applications for it, like a replacement for sutures which is impervious, just like sutures are, to water and other conditions.

All of which is very cool, but before I shell out for one of those robots, they’re going to have to teach it how to eat spiders.

Now you know.

 
 

 

 
Copyright © 2014 Randy Fry

By |2017-05-24T00:03:06-05:00June 30th, 2014|Nature Essays|1 Comment
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Iguana iguana

It sucks to be an iguana.  That’s why they have that look on their faces.  If you’re an iguana, everyone just wants to eat you.  You’re a gentle vegetarian who wouldn’t harm a fly, but all it buys you is a job as the main protein source for an entire food chain.  If you’re an iguana, you’re a talented survivor in three different ecosystems—you’re a terrestrial animal who can become aquatic in a pinch or become arboreal in a different pinch, but it doesn’t do you any good because you’ve got predators in all three places.  Even human beings have been eating iguanas and their eggs for over seven thousand years, and call them gallina de palo, chicken of the tree.  And now they’re being captured live and imprisoned in peoples’ terrariums.  Iguanas don’t get any respect.

And they’re all around us here in Akumal, Mexico, where Susan and I now live, so I thought it was as good a place as any to start transitioning my Ranger Randy articles to the tropical biome.  I looked into these large and handsome reptiles.

The green iguana (Iguana iguana, a name worth repeating) is a tremendously successful animal throughout south and central America, and they’re seldom green.  Susan and I photographed the one above in Costa Rica.  He’d clearly had a close brush—Susan calls him “Not the fastest iguana in the forest.”  He’s a male, and the orange tone is breeding coloration.  He’s maybe three feet long, but if they live long enough (which only a few do) they can reach five or six feet, and at that point they are well-armored and formidable lizards capable of defending themselves.  They have claws, razor-sharp teeth and a dorsal crest of wicked spines that runs all the way down their back, and people who know have told me that you don’t want to get lashed by that tail.  Even so, there are predators in these forests who can easily take them down.  Just the line-up of cats in American tropical forests can give you the shivers, ranging from the tiny jaguarundi up through the ocelots to the huge and magnificent jaguar.  It’s a fearsome place to call home, and it has made the iguanas tough, and good at what they do.

Standing_jaguar--4-3
Jaguar (Panthera onca)
By USFWS
[Public domain], via Wikimedia Commons

They like to hang out in trees for safety, and to soak up rays (thermal-regulate), and for a little extra margin, they like for the trees to be over water.  If you run a river in Central America you can always see them lounging around way up there above your head.  They do this so that if they are attacked from the air, they can take a dramatic, flying leap, plunging thirty, forty or fifty feet down into the water to hopefully escape.  One nature guide we talked with had seen an iguana do this to escape a harpy eagle, and he hit the water only to be pursued to the far bank by a crocodile.  They’ll even take a leap like that with no water around, and can survive a fifty-foot fall to the forest floor, braking themselves by shredding passing foliage with their hind claws as they plummet.

They breed like rabbits, and that’s because they actually occupy a similar ecological niche, being a primary herbivore at the base of the food pyramid.  A female will lay up to sixty-five eggs in a burrow, and she doesn’t go in for parental nurturing.  She lays the eggs and leaves, and that’s the end of that.  The young fend for themselves right out of the eggshell, but they help each other through, staying in a family group for the first year, using the more-eyes-is-better philosophy, or, as scientists call it, the “selfish herd” behavior.

Their range is growing, and not for good reasons.  It’s not clear if they were always as far north as Mexico, and they can be considered invasives here depending on who you talk to.  But for sure they never belonged in Texas, south Florida or the Hawaiian islands.  Puerto Rico wants to eradicate theirs.  They have been introduced in all those places as stowaways on produce ships, or as escaped or released pets.  They’re darlings of the pet trade right now.  Everyone thinks they’re cool, but they’re actually very difficult to care for, and most of them perish within the first year, or—an even worse crime—get released into the wild by their owners, all of which is just one more reason (as if we needed one) not to go around caging wild animals.  In 1995, though, an interesting thing happened.  They suddenly colonized the Caribbean island of Anguilla, where they had never been before, and a scientist named Ellen Cinsky was able to figure out, with some significant biological and oceanographic investigation, that a raft of trees uprooted by a hurricane and containing a clutch of iguanas had drifted two hundred miles from another island over a period of three weeks, proving that it is not always human beings who mess up ecosystems by introducing species.

They have a “third eye” on the top of their head called a parietal eye, which is a very primitive form of light receptor also found in some amphibians and fishes.  It is not capable of forming images but can detect something like the passing shadow of a raptor, and also guides their thermal-regulation.  But their thermal-regulation only goes so far.  At the end of the day these creatures are cold-blooded (ectothermic) and anything below about seventy-nine degrees farenheit puts them in a stupor, which is what led to the 2008 frozen iguana showers in south Florida.  Bear with me.  A rare cold front passed through, and the iguanas in the trees became insensible and lost their grip, and were falling out of the sky all over the place.  The sidewalks and bike trails were littered with them.  Later in the day when it warmed up most of them were able to stumble off and resume their lives.

Now you know.

 
 

 

 
Copyright © 2014 Randy Fry

By |2017-05-24T00:03:06-05:00May 29th, 2014|Nature Essays|Comments Off on Iguana iguana
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Farewell to the Gray Coast

I love these woods when they’re wet.  A thunderstorm crashed through last night, and the pine duff is soaked, drenched through, a glistening, springy, cinnamon-colored cushion as big as the whole forest.  My awareness reaches, unsatisfied, beyond my body as I run the trails, and I am imagining the give of the wet carpet under my bare palm.  My mental hand reaches out and touches the rough water-darkened bark of oak trees as I pass by, shakes a silver spray of droplets from a spun festoon of lace lichen, reaches into a puddle and feels fine clay mud under half an inch of icy water, while my legs go on pounding, my lungs go on breathing.  The air is cold and clean, and it’s starting to rain again, pelting against my chest and soaking the tops of my aching thighs, but I’m not cold, I’m high.  My burning muscles vault me over a new windfall, and a chaos of fallen foliage showers me with water.  At the top of a rise I throw my tired head erect and look out, far out, over the misty ridges, under the rainclouds, and there it is, the Monterey Bay, gray within gray within gray.  Five thousand feet deep where I’m looking. 

 

I wrote those words in 1992 and my love for this peninsula is undiminished.  Susan and I have hiked its trails, kayaked its waters and run its marathons.  We have walked the fields of lupines in sunny springtime meadows, and hammered out training runs through icy rain and hail on Big Sur ridge tops.  We have powered our kayaks through the angry waters off the Point Lobos headlands where Robinson Jeffers wrote brooding pieces about the gray coast.  We have crossed the Monterey Bay, we have hung out on the tops of the canopies of the great kelp forests, and we have poked around in networks of sea caves where the water beneath us is under-lit by green light from mysterious submerged portals, and the only sound is the slow suck-and-draw of the breathing of the great ocean.  We have explored this place completely and intimately, as lovers should.

On Thursday we leave it.

The place we are going would be called, by most reasonable definitions, paradise.  We will be on a Caribbean coastline in Mexico.  We will be walking among Mayan ruins, and kayaking turquoise waters without wetsuits.  The birds will be wild, loud and colorful, with long tails or absurd beaks, and there will be monkeys in the jungle canopy and tropical fish in the estuaries.  We will have a whole new ecosystem to learn.  But one never really leaves the Monterey Peninsula.  I know this.  I have been haunted by it before.

Susan and I have sold everything we own that will not fit in a pickup truck.  A lifetime of acquisitions are gone and we have not suffered a moment of remorse.  We will have each other, our dog Rita, two ocean kayaks, and a few boxes.  On Thursday we step on the gas.  Really it is a crossing—there are no beaches, there is no bail-out.  And that’s just the way we like it.

We are the luckiest people in the world, to have each other, and to have this life, and I’m certainly not complaining….

…but God dammit, I’m going to miss this place.

 
 

 

 
Copyright © 2014 Randy Fry
By |2015-08-31T11:15:41-05:00May 1st, 2014|Nature Essays|1 Comment
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Falcons With Mean Streaks

So picture this:  You’re a pigeon.

You’re a pigeon and you’re whizzing along a hundred feet above an open area.  You’re whizzing along and you notice a speck in the sky two thousand feet above you.  You notice a speck and then you notice that it’s dropping toward you.  It’s dropping toward you and when it turns out to be a peregrine falcon, you are so screwed…

If there were some trees or brush to drop into you might be okay, but that’s not where peregrines hunt.  There is nowhere to fly to and nowhere to hide, and it seems so unfair, because you’re a pigeon, for God’s sake, you’re one of the strongest fliers on the planet.  You can sustain forty miles per hour in level flight, which that peregrine up there couldn’t dream of doing, but even as that thought crosses your mind, the peregrine crosses the hundred mile per hour mark because she’s tucked, she’s in a vertical dive, plummeting at you like a bullet and still accelerating.  You pour it on, but as you’re approaching your top sprint speed of sixty miles per hour the peregrine breaks a hundred and fifty.  Nictitating membranes shutter across her eyes to shield from the screaming wind.  You see a distant grove of trees but you know you won’t make it.  The peregrine breaks two hundred miles per hour.  At two-forty she opens her wings ever so slightly and starts to pull out of her dive behind you, making a sound like canvas ripping, pulling twenty-seven G’s and briefly weighing fifty-nine pounds, and then she flashes into you still doing almost two hundred miles per hour, but she doesn’t grab you. 

She hits you.

*          *          *          *

The pigeon is killed instantly and painlessly, though that’s not always the case with a peregrine kill.  The impact is like being hit by a high-speed projectile and it shatters the spine at the base of the skull.  As the pigeon tumbles lifeless through the air, the falcon slows to a sane speed, circles around with a couple of flaps, and snags him in mid-air, then flies off to find somewhere safe to eat.

Susan and I chat about cheery things like this all the time, and as we were remarking over cocktails last night about how amazing peregrine falcons are and how much it must suck to be a pigeon, I brought up that remarkable technique they have of hitting their prey instead of grabbing it, and Susan asked a great question.  The question went like this:

Hit it with what??

With their head, for God’s sake?  With their breastbone?  What could they possibly hit it with?  They don’t carry a club or a mace.  How the heck do you hit something—at two hundred miles per hour—without both of you becoming lifeless puffs of feathers?

I had no clue, and Susan doesn’t let me make stuff up, so I had to dig into this a little.  I managed to find it, and of course along the way I learned some amazing stuff I hadn’t known about peregrine falcons, so a Ranger Randy article was warranted.  Here you go:

First of all, to answer Susan’s question, they hit them with—if you’re ready for this—a clenched foot.  I kid you not.  They hit them with their fist.  At least that seems to be the prevailing opinion, though there’s still argument.  One fairly auspicious scientist (and falconer) named Tom Cade absolutely insists that they strike with an open foot, even claiming that they rake the rear talons across the back of the bird, but most of the world including me finds that hard to picture.  I just can’t imagine a falcon retaining  possession of all his toes for very long if he went around doing that.  (It’s delightful that we still don’t know this conclusively—falconry has been a sport for four thousand years.)

But what absolutely flabbergasted me was that number up there—that three-digit one.  That’s a confirmed number.   There’s a guy named Ken Franklin in the San Juan Islands in Washington state who is a falconer and a pilot and a skydiver and the husband of an ornithologist, making him probably the only person on the planet who could have concocted a way to clock a peregrine in a dive.  He affixed a tiny altimeter to a feather shaft on the rump of his female peregrine falcon and took her up in a light aircraft to 15,000 feet, then falcon and falconer both jumped out of the plane.   He then dropped what falconers call a lure, which is a leather-covered weight with some feathers involved so it looks a little like a bird.  The falcon went into her dive, which is called a stoop, and she achieved two hundred and forty-two miles per hour pursuing that thing through the vaults of sky.  (You can watch the Youtube here.)  Now, let me just hazard a few comparisons regarding that number:  That wind speed will peel the skin off an airplane if it has some missing rivets.  The most intense hurricane on record, Wilma, in 2005, only had winds of 185 mph.  My brother Gary is going to take me up flying in a few weeks, and the top speed of the Cessna aircraft we’ll be in is only 188. The closest I’ve come to feeling those kinds of winds was 110 miles per hour.  That was a skydive, and it was a fight to keep my cheeks on my face.

The posture of a peregrine falcon during a stoop has been called hyper-streamlined.  They are a heavy, compact, small-winged bird in the first place, and when they go into their stoop, they assume a perfect teardrop shape, like a tiny torpedo.  I’m not built as well for that kind of thing, so wind resistance held me to a pokey 110 mph, but some physicists did a study testing the flight physics of an “ideal falcon” and calculated that terminal velocity for them is 250 mph at sea level (confirmed by Ken Franklin’s experiment).  At high altitude, they figure maybe 390.

That’s half the speed of sound.

When they kill smaller birds like songbirds they can just overtake them and grab them like any other hawk, but the larger ones they will hit.  They often hit something too large to carry, and in that case they will follow it to the ground and chow down there. If they were only able to stun or disable the bird, they dispatch it with a special adaptation to their beak shape called a tomial tooth, designed to quickly sever the spine.  They have been observed killing birds as large as a sandhill crane, which is a wading bird that stands as tall as your chest.

They prefer not to eat on the ground, though, because they do have their own predators.  Raptors like the golden eagle or some of the larger hawks will drop on the peregrine in their own stoop if they catch her on the ground, and the peregrine is not the fastest bird in level flight.  With the tables turned, she will not be able to escape.  This might explain the mean streak they have where large hawks are concerned.  A peregrine will kill a red-tailed hawk given the opportunity.   The red-tailed is too big for her to kill outright, but the falcon will come streaking through from out of nowhere and break one wing.  The hawk will spin to the ground, crippled, where he will probably die a very slow and painful death by starvation, without even the hope of a merciful killing by another predator.  As Robinson Jeffers says in his wonderful poem, Hurt Hawks, “There is prey without talons.”  This is probably what befell the hawk he writes about.

Peregrines like to hang out on extremely high perches above open areas with little cover, so they’re fond of bluffs above bodies of water.  We have a pair here in Monterey, California who hang out on the “E” of the lighted sign on the top of the Embassy Suites high-rise, above a nice lake with lots of waterfowl.  If there’s not a high perch around they will circle as high as three thousand feet above the hunting ground, so high they’re not even visible to creatures like us.  They have incredible eyesight.  Their eyeballs are huge, they just don’t look like it, because unlike us, only the iris and pupil are exposed.  Their eyeballs actually take up most of their skull, leaving little room for other sundries like a brain.  (That’s also why owls don’t owe their survival to their intellects—a barred owl has a skull the size of a golf ball and two human-sized eyeballs in it.)

Peregrines were once a very successful bird with a world-wide range, but we almost managed to kill them off completely by dumping the “harmless” pesticide DDT into our environment for three decades.  The poison magnified up the food chain and the falcons took a bad hit.  It robbed them of their calcium and the eggshells would all break before the chicks could hatch.  In a rare example of doing something right, we outlawed the stuff in the nineteen-seventies, and peregrine falcons rebounded, and are back off the endangered species list, a conservation success story.  It can be done, when we have the will.

So that’s the news on the peregrine falcon.  Fastest creature on the planet, proud and noble, but also with a mean streak.  Oh, and they’re fastidious:  Before they eat their prey, they pluck it.

Now you know.

 
 

 

 
Copyright © 2014 Randy Fry
By |2017-12-09T07:28:47-06:00February 15th, 2014|Nature Essays|Comments Off on Falcons With Mean Streaks
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Ravens in the Service of the Crown

There are ravens in the Tower of London.

Which may not sound that remarkable, but the reason it’s sort of weird is that ravens (Corvus corax) almost do not exist anywhere else in the British Isles.  They were largely exterminated over a century and a half ago when it was thought that they killed baby livestock.  Ravens cannot do that.  They cannot kill a healthy newborn calf, but they are carrion eaters, and when a farmer would walk out and find a dead baby calf with ravens pecking out its eyes, he would come to the wrong conclusion.  Unjustly accused, the ravens, after co-habiting with the English for many centuries, suddenly, due to some inexplicable turn in public opinion, became pariahs, victims of prejudice, and a great cleansing ensued.  A raven genocide swept across the English landscape, and as firearms became more widespread, their fate seemed sealed.  What saved them is that ravens are corvids, and can learn and teach, and they quickly started avoiding humans, and teaching their young to do the same.  Nowdays, they only exist in the highlands and the outlands, nowhere near human habitations.

Corvus_corax_London
Common Raven (Corvus corax) at the Tower of London
By Philippe Kurlapski,
[CC BY 1.0], via Wikimedia Commons

But a small colony nests in the Tower of London, right in the center of the city, and there is great speculation about how in the heck they ended up there.  The answer is lost to us, but the ravens have become a storied part of English society, because there is a superstition in England which goes something like this:  If the ravens ever leave the Tower of London, the British government will crumble, and a horrible fate will befall all her people.

Taking no chances, the British government clipped their wings.  They can fly a little way, but not far.  There is a full-time ravenmaster at the Tower of London, and a staff to care for them, and the birds are carefully nurtured and luxuriously fed, and are very close to the hearts of the royalty-loving British public.
Administratively, the ravens are enlisted as soldiers in the British army, and each has a leg band with identification, and an attestation card like anyone else in the service of the Crown.  And they can be dismissed for unsatisfactory performance, too.  One was let go for attacking television antennas.  Another was able to fly a short distance away and took up residence in a local pub, and was discharged for conduct unbecoming.

Several decades ago one of them was kidnapped.  He was never found and the crime was never solved, and in the substantial body of English folklore that surrounds unsolved crimes, this one rates right up there with Jack the Ripper.

I saw the ravenmaster interviewed on TV once.  The interviewer politely asked him whether he actually believed this superstition, and whether he was able to take his job seriously.  A philosophical look crossed the fellow’s face.

“Well,” he said, in his charming Londoner accent, “I look a’ it this way:  if the ravens were to leave the Tower of London…and if the British government did crumble…and a ‘orrible fate did befall all her people…I’d have a lot to answer for, now wouldn’t I?”

Now you know.

 
 

 

 
Copyright © 2014 Randy Fry

By |2017-05-24T00:03:07-05:00January 26th, 2014|Nature Essays|Comments Off on Ravens in the Service of the Crown
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