by Matt Simon
Really, the asp caterpillar is a crawling head of hair—flowing, golden locks that make the creature look like it fell asleep under a blow-dryer. Like other caterpillars, it goes through molts as it develops, in which it sheds its exoskeleton and grows a bit bigger. But at each stage, the asp caterpillar adopts an ever more luscious hairdo, until it ends up with a wispy, inimitable ’fro. Yet it’s not the hair that’ll ruin your day. It can irritate your skin, sure, but it ain’t got nothing on what lies underneath: spine after spine after spine, each attached to a venom gland, and each capable of delivering toxins to those unfortunate enough to assault the creature.
SNAKE EYES
Oddly enough, there are other species of moth, in the genus Hemeroplanes, whose caterpillars aren’t snakes in name like the asp caterpillar—they essentially are snakes. They’ve evolved to look like serpents, each with a bulbous end that mimics a snake’s head, complete with big black eyes and a pattern that resembles scales. The caterpillars even behave like snakes, holding on to branches with one end of their body while moving the head around sinuously like a serpent might. It’s a bluff, sure, but it’s a damn good one at that.
And asp caterpillars can appear in expansive numbers. In Texas they’re a particular problem, where the things have been known to blanket trees. Officials have had to shut schools down because children, thinking the fuzzy caterpillars must be cuddly, pick them up. In 1923 the USDA noted: “In Dallas and other Texas cities hundreds and even thousands of cases of stings have occurred during a single season, and in some cases the fear of the caterpillars became almost a mania owing to the description of the effect of the stings which was passed from one to another.” The report’s author, speaking like someone who had never been the victim of a caterpillar, added: “It is possible that the effects of stings may be made more serious by the hysteria engendered by these often exaggerated statements, especially if published in newspapers.”
One of the more elaborate accounts of an asp caterpillar sting comes from North Carolina in 1997. A man was cleaning fish when he reached into his cooler and felt a severe burning in his arm. Sitting there on his limb without the slightest care in the world was an asp caterpillar. With admirable foresight, the man showed up to the hospital carrying the caterpillar “in a cellophane-covered plastic cup.” It was a good effort, though it wasn’t as if the doctors could do anything special if they knew what attacked him—the caterpillar’s venom isn’t nearly as well understood as that of something like a rattlesnake because, let’s face it, there aren’t many grad students lining up to devote their lives to studying hairy caterpillars.
YOU KNOW, NOW THAT YOU MENTION IT . . .
The asp caterpillar sports what are known as urticating hairs, meaning they’re irritating to the skin and mucous membranes. Tarantulas also have them, kicking the hairs off their bums when threatened, to create a cloud of misery. A twenty-nine-year-old British man found this out the hard way when in 2009 he visited the ophthalmologist complaining of an itchy, watery eye. Only when the doctor informed him that he had tiny hairs embedded in his eyeball did the thought occur to him that maybe, just maybe, it was the dose of urticating hairs his pet tarantula had hit him with three weeks earlier. He’d been cleaning its tank with the tarantula still in it, when the predictable ensued. As the doctor recounted: “He turned his head and found that the tarantula, which was in close proximity, had released ‘a mist of hairs’ which hit his eyes and face.” Having treated the patient, the doctor seemed happy to add that the man “now wears eye protection before handling the tarantula.”
Upon arrival, the man told the staff he was experiencing the worst pain he’d ever felt, noting with what I imagine was total sincerity: “It feels like my chest is caving in.” What follows in the account is mostly a hodgepodge of medical terminology, but here are a few highlights. Initial symptoms were dry mouth (eh, no big deal), vertigo (okay, getting serious), and difficulty breathing and swallowing (definitely serious). Doctors pumped the man full of pain meds, plus some antispasmodics to treat the twitching in his upper leg, and then some more pain meds to be sure. Thus, filled to the brim with drugs, our brave patient stabilized, no doubt with a finer appreciation of caterpillars.
Other critters have not only taken notice that it’s not a solid idea to mess with these things, but that stinging caterpillars got it made. One bird, the cinereous mourner, even seems to mimic hairy caterpillars. As a chick, it develops long orange plumage that bears a striking resemblance to the outfit of a stinging caterpillar it shares a habit with. Nature, it seems, is full of creatures more than willing to bite your style.
Ocean Sunfish
PROBLEM: With so many predators about, releasing eggs into the open ocean is asking for trouble.
SOLUTION: If you’re the ocean sunfish, you subscribe to the spray-and-pray method of reproduction, dropping a world record 300 million eggs in a single go. After all, someone is bound to survive.
It’s a brisk-but-not-uncomfortably-brisk January morning, and marine biologist Tierney Thys is on a lawn kneeling over the biggest bony fish in the world. Well, this particular ocean sunfish could well have been, had it not died just a year into its life and washed ashore. The animal is flat and circular, a bit bigger than a dinner plate. Its eyes are gone, probably stolen by gulls that couldn’t peck through its thick skin to reach any other meat. Also missing are its two towering fins, which normally sprout from its back and belly. Those were probably snagged by sea lions, which have been known to nip them off and then toss the fish back and forth like a Frisbee.
Gathered around Tierney are two dozen teachers, who are ostensibly here to learn how to better communicate science to their kids, but who now appear to have become the kids, giggling and oohing and aahing and snapping photos. Tierney plunges her scalpel into the sunfish, cuts away a chunk of the sandpapery skin, and passes it around. One teacher asks her to walk us through the digestive system so she could film it and show it to her kids, whom she’s teaching about such things at the moment. Tierney obliges, pointing out its stomach and lifting up its pearl white intestines.
But I’m more interested in the genitals. I can’t say that in front of two dozen teachers, so I wait for them all to file back inside for their conference, and then ask Tierney if it’s a boy or a girl. I’m disappointed to learn that it died too young to tell such things, for I wanted it to be a girl, and I wanted to see her eggs. The ocean sunfish, which grows to ten feet long and two and a half tons, can release 300 million of the things, more than any other vertebrate. And that was estimated from the ovaries of a four-foot female, which hadn’t even grown to half her potential size.
The ocean sunfish takes a laid-back approach to whoopee: spray-and-pray reproduction. Because the female is so enormous, and her eggs are so tiny—about the size of a BB gun pellet—the sunfish can pack a ton of them into her body. And it’s a good thing she can. Like most fish, the sunfish utilizes external fertilization, with the female dumping eggs into the water as the male dumps his sperm. With any luck, the two parties will meet and fertilization will commence. Afterward, the female doesn’t care for her kin in the least bit. She disperses her millions upon millions of eggs and swims away.
Thus the ocean sunfish plays no small part in contributing to the biomass known as plankton. Plankton are teeny-tiny life-forms at the mercy of currents. Think microscopic plantlike organisms, called phytoplankton—whose photosynthesis is responsible for producing half of the oxygen in our atmosphere—as well as animals, called zooplankton. Then there are the eggs like the ocean sunfish’s. Collectively they are a monumentally important source of food in our seas for all manner of predators, from tiny shrimp on up to the sixty-five-foot-long whale shark (which, as it happens, is the biggest fish, bony or otherwise—it has a skeleton made of cartilage instead of bone). And that’s a problem if you’re a sunfish egg that’d prefer surviving. There’s so many of them, though, that a few are bound to make it.
&n
bsp; THE UNGLAMOROUS LIFE OF THE PENIS-FACE FISH
There are a few weirdos when it comes to fish sex, such as the penis-face fish of Vietnam. The male has an organ on the underside of his face, with a serrated, hooked bit that grasps on to the female as another bit shoves a sperm bundle into her naughty parts, which are also on her throat. Oh, I should mention. They defecate out of their face sex organs as well. So now that’s something you know.
If the eggs can manage to develop into larvae they have another trick to make it into adulthood, one that gives away their heritage. Ocean sunfish, as it would turn out, are highly modified puffer fish, which long ago left the reef for life in the open ocean. Adult ocean sunfish may have lost their spikes, but the larvae have retained the weapon of their ancestors. The youngsters are almost spherical, with doe eyes and huge conical spikes jutting in all directions. It isn’t hard to see just how beneficial these spines would be out in the vast sea, for there are no reefs to cower in or sand to burrow into. There’s only hungry mouth after hungry mouth, which may not appreciate spiky prey. As the sunfish develops, these spikes shape-shift to become thinner and pointier, until they disappear almost entirely as the larva enters the adult form. The minute projections remain, though, helping give the sunfish’s skin that sandpapery texture (it’s still rough enough to rip up human flesh, as Tierney, who spends her days tagging the sometimes uncooperative creatures, can attest).
INTO THE BELLY OF THE BEAST
When he was sailing around the world on the Beagle, Darwin, off the coast of South America, was “amused by watching the habits” of the porcupine fish, a species related to the puffer fish, with the same ability to inflate itself, thus deploying those famous spines. He was under the mistaken impression that should a shark snag one of these critters, it wouldn’t be the spikes the predator would have to worry about as much as the porcupine fish gnawing its way “through the sides of the monster, which has thus been killed.” That’s a nice underdog story, but it isn’t so much possible. Darwin would return to England and come up with the best idea of all time, so we’ll go ahead and give him a pass on this one.
When the sunfish tops out at ten feet long and thousands upon thousands of pounds, it’ll set yet another record in the animal kingdom. From a larva measuring a fraction of an inch long, it will have grown in size 60 million times, the most epic growth among the vertebrates. That’s like you coming out as an eight-pound baby and developing into a human that weighs a half billion pounds.
Yet of the 300 million eggs the female sunfish releases, only a fraction will survive long enough to realize that growth. We know this because, for one, if a lot made it, the oceans would be lousy with sunfishes. And also because although populations of a given species may fluctuate—say, due to the arrival of some cataclysmic outside force or the departure of a competing species—on average only two of an animal couple’s offspring will survive to reproduce, thus replacing their parents in the population (we humans and our explosive numbers are a notable exception, having excused ourselves from the food chain). Just two. In the case of the ocean sunfish, two of 300 million potential fish.
But in the end, the mama’s big bet pays off. She doesn’t stick around to watch her kids dodge their first whale shark attack or lose their first spikes or finally become adults with responsibilities and stuff, but in her own way she ensures their survival, however few of them make it. Her solution to the problem of predation is to overwhelm the ecosystem with sheer numbers. It ends up being a massacre, sure, but it’s a massacre with a happy ending, which is the best kind of massacre of all.
Lowland Streaked Tenrec
PROBLEM: The forests of Madagascar are home to plenty of hungry mouths.
SOLUTION: The lowland streaked tenrec is the only mammal that can communicate with stridulation, rubbing quills on its back to make chirping noises that reel its straying kids back in.
There’s no better way for a parent to tell his or her child “I don’t trust you and I trust myself even less” than putting the child on a leash. I mean, I kind of get it. You wouldn’t want to lose your kid. We are, after all, mammals that don’t have the luxury of pumping a few hundred million eggs into the world and hoping for the best. Human moms don’t have that many chances to pass their genes along—but let’s be real, maybe a leash isn’t the most elegant way to hold on to your kids.
In the absence of leashes and the opposable thumbs required to operate them, an enchanting mammalian mother in the forests of Madagascar, called the lowland streaked tenrec, has hit upon a more punk-rock solution to losing her meandering kids as the family forages at night: spikes. While the tenrec is streaked with bright yellow and black spines, making it look like a hedgehog that dressed up as a bumblebee for Halloween, there’s a cluster of thirteen to sixteen specialized spikes running down the mom’s back that she rubs together to produce a high-pitched noise, which sounds a bit like rapidly running your finger up and down the teeth of a comb. It’s the same principle behind a male cricket chirping by rubbing his wings together in order to attract females, but no mammal other than the tenrec can communicate in this way, a technique known as stridulation. But then again, there’s no mammal quite like the lowland streaked tenrec.
SO HOW WILL WE KNOW WHEN THERE’S AN AWKWARD SILENCE?
There’s a tradeoff to all this commotion: Stridulation helps the tenrec find its family and the cricket find a mate, but it can also attract unwanted attention. A remarkable illustration of this comes from the field crickets of Kauai. In the 1990s an invasive parasitic fly arrived on the island, a menace that homes in on crickets by their chirping and deposits its kids on their backs—maggots that then burrow into their hosts and eat them from the inside out. At some point, though, a mutation arose that made male field crickets incapable of chirping, rendering them largely invisible to the fly. Natural selection therefore favored those crickets, as their chirping colleagues perished: In only twenty generations the population had almost entirely shifted to nonchirping males. However, this in turn made them less conspicuous to females, which love themselves a good chirp. It seems the females arrived at a compromise, accepting the mutes as they are, probably because they have no choice on account of all the chirpers being eaten alive.
Who says romance is dead?
Tenrecs have done well for themselves on Madagascar. The island was once part of the supercontinent Gondwana, but set out on its own almost 90 million years ago. Some 30 million years later, a small mammal made it to the island, splitting into different species of tenrec that assumed different niches. There’s a water-loving tenrec with webbed feet, for example, while other tenrec species take to the trees. The lowland streaked tenrecs became nocturnal, social foragers, forming into groups of as many as two dozen individuals to root around the forest floor with their long schnozes, all the while communicating in the darkness by stridulating. A momma lowland streaked tenrec can have eleven kids, quite the handful when you consider that tenrec clans fan out as they forage, and each infant may wander ten feet away from the mother. So amid the racket of the rain forest, the distinctive note of stridulation acts as a beacon for any lost children.
The scientist who revealed much of this strange communication, in the 1960s and ’70s, was a man named Edwin Gould. He had a hunch that stridulation was a mother’s way of keeping track of her kids, so he set up a square arena with speakers in two corners, dropped a young tenrec in, and put on the sweet sounds of rasping quills. Of the nineteen infants he tested, fifteen made a beeline for whatever speaker was active. In a second experiment, this time in an outdoor enclosure, he immobilized a mother tenrec’s stridulating spines by slathering them in glue. While youngsters typically feel free to wander, now they followed much closer, likely using scent instead of the stridulation to pinpoint her position.
But this is more than a matter of not getting lost, for the tenrec isn’t the only predatory mammal that’s made it to Madagascar. There’s also the Malagasy ri
ng-tailed mongoose, with its gorgeous alternating bands of black and burnt orange to rival the lowland streaked tenrec’s own lovely color scheme. Also stalking these forests is the fossa (pronounced FOO-suh), which looks like a cat but is more closely related to mongooses. Present the odor of either of these predators to a tenrec, as Gould did, and you’ll get yourself quite a reaction. The nonstridulating spines at the back of the tenrec’s skull, which normally lie flat, perk up and over the head into what looks like a spiky, bright yellow lion’s mane, as the critter emits a putt-putt sound. If whatever is threatening it isn’t impressed, the tenrec escalates the noise to a kind of crunching and starts bucking its head, driving the detachable quills into the villain’s snout or paw.
IN LIVING COLOR
Certain brightly colored organisms presented Darwin with an evolutionary conundrum. Sure, sexual selection is often at play here, the females of a given species preferring flamboyant males over drab ones. But why on earth would, say, the larval form of an insect adopt extravagant hues? After all, it has no mates to win over. Darwin forwarded the problem to Alfred Russel Wallace, who cracked it. It’s a warning, Wallace realized, that alerts predators to the toxicity of the prey, since there’s no point in being toxic if something is going to gobble you up whole, as both parties may perish. You need some sort of signal. The lowland streaked tenrec isn’t toxic, but it sure as hell is dangerous, and signals as such.