by Matt Simon
Unlike the zorilla or the skunk—whose piebald colorations serve to warn predators that they aren’t to be trifled with—by exposing those black and white hairs when threatened with attack and turning one of its sides to face its foe, the crested rat may well be inviting a bite. I mean, clearly it’d be ideal not to be assaulted in the first place, but if the rat is going to get bitten anywhere, it wants to get bitten on those toxic hairs. That’s how confident it is in the speed with which the poison sets in.
WEAPONS OF MASS CONSUMPTION
The crested rat may appropriate the toxins of a plant, but there’s a beautiful sea slug out there, the blue dragon nudibranch, that appropriates the weapons of one of humanity’s most feared oceanic menaces: the Portuguese man-of-war (which, fun fact, isn’t a jellyfish but a siphonophore, a kind of colonial organism made up of a bunch of clones). But the blue dragon doesn’t take the man-of-war’s stinging tentacles and apply them to its body. No, it straight up eats the things. Somehow, someway, the stinging cells make their way through the walls of the nudibranch’s digestive system and end up in its skin, ready to torment anything foolish enough to touch the creature. Sure, it doesn’t breathe fire like a dragon, a challenge when you live underwater, but its burn is just as devastating.
Should the diversion fail, though, the crested rat comes equipped with a few other handy adaptations. While it may look cute and fluffy, it’s built like a linebacker, with an armored skull and beefed-up vertebrae, not to mention tough, dense skin. That skin is so tough, in fact, that researchers once examined the corpse of a crested rat and found that it was heavily bruised as if a dog had mauled it, yet the skin hadn’t been punctured. This is a creature that has evolved to take a beating.
Dogs seem to have a particular fondness for molesting the rats, while lacking a particular immunity to the poison. Accounts of attacks have been numerous, and often brutal. The scientists who first studied the structure of the crested rat’s special hairs noted that symptoms among canine attackers “range from mild lack of coordination, mouth-frothing and signs of general distress to collapse and rapid death, apparently from heart failure.” Other dogs have fared better, recovering from their stupor after a few agonizing weeks. And at least one prudent pup that “survived a putative near-death encounter displayed every sign of fearful aversion” when it came across another crested rat.
The Acokanthera is clearly a tree of staggering toxicity, which should therefore elicit the question: How is the crested rat itself not dropping dead after getting a mouthful of the stuff, when all that’s needed for any other creature to drop dead is, well, getting a mouthful of the stuff? No one knows for sure, but a clue could be the rat’s outsized salivary glands. It may be that the crested rat’s saliva has some kind of protein that binds to ouabain, the compound that gives the Acokanthera its toxicity. We’d also expect the rat to be ingesting at least a little bit of the stuff, so perhaps its digestive system is also adapted to handle ouabain.
HAIR-RAISING EXPERIENCES
You know how cats do that thing where they bristle their hair when they’re all worked up? They’re trying to make themselves look bigger to fend off an enemy. It’s a brilliant little strategy, and it turns out that we have remnants of it in ourselves: goose bumps. Humans descended from some sort of mammal that raised its hair to look bigger, and when our adrenaline kicks in for whatever reason, the thin hair we have left still tries to go erect. And when you get goose bumps from the cold? Our ancestors probably used the same mechanism to raise their hair, thus trapping a layer of air to better insulate themselves. As for the geese, well, they just have bumpy skin. What are ya gonna do.
Getting eaten is bad, and the crested rat has stumbled upon a truly inventive manner of avoiding it. But evolution abhors an advantage. As creatures evolve defenses, their predators evolve workarounds, and as the prey evolve even better defenses, the tug-of-war goes on and on. We all must eat, after all. And when it comes to eating, our next batch of critters simply won’t suffer starvation.
These are Earth’s most insatiable appetites.
CHAPTER 6
It Turns Out Not Eating Is Also Bad for Survival
In Which Primates Give Us the Finger and Beetles Run So Fast They Go Blind
There is, of course, the other side to all this predation: the gluttons themselves. I mean, a foot-long snail’s gotta eat, even if it means laying waste to Miami. As does a certain crustacean (not the Miami bit—the having-to-eat bit), so it’s evolved to blast through clam shells with shockingly powerful punches. Think Mike Tyson, only with more legs and fewer face tattoos.
Giant African Land Snail
PROBLEM: A snail has to eat not only for energy, but to build its shell.
SOLUTION: The giant African land snail lays waste to vast swaths of vegetation. And when the snail invades Florida and can’t get enough calcium to build that shell, it lays waste to the stucco in vast swaths of homes.
I want to be clear about something: I’ve got nothing against Florida. I went there once, and the weather was great. But Florida is a . . . singular place. Again, nothing against it, and I’m not just saying that to avoid alienating a market for this book. But whenever you hear that a guy flashed his bum at an IHOP in a quixotic attempt to get free food—and that was only after impersonating a cop didn’t do the trick—you think, “Oh, Florida, it has to be.” And sure enough it is (specifically, in Orlando in January 2014). Or when a guy dials 911 to check up on that tax return of his. Yep, Florida again (a month later in St. Petersburg). Or when foot-long creatures called giant African land snails maraud neighborhoods devouring houses. It could only be Florida, and I say that with all due affection.
I’VE ASSAULTED SNAILS WITH SALT, AND FOR THAT I’M SORRY
If you were once an adolescent idiot like me, you poured salt on snails and said mockingly, “I’m meeelting!” because you were cruel and too young to realize that’s a dated cultural reference. It was terrible behavior, and I’m sorry for doing it. In reality, salt doesn’t “melt” the snail. That foaming is the salt drawing the water out of the animal, which dies of dehydration. Again, I’m sorry, both for salting snails and for the dated cultural reference.
Florida has a very, very bad and very, very giant snail problem, where the critter has become an invasive fiend. Part of the problem is that these snails have a pretty good thing going. Like the penis-fencing flatworms, they’re hermaphrodites, so one sexually mature giant snail is always capable of mating with another sexually mature giant snail. And like the flatworms, two snails can fertilize one another. They’ll then go off and lay up to four hundred eggs, and as many as 1,200 a year over their ten-year lifespan. As if that weren’t enough, giant African land snails can store their mate’s sperm for up to two years, fertilizing multiple batches of eggs. It all adds up to some serious potential for invasiveness.
The problem is particularly bad in Florida because the snails have no natural enemies there. Plus, their colossal size, which allows them to muscle out native species of snails, isn’t helping either. They can eat pretty much any plant material, over five hundred species in Florida alone, making them a nightmare for gardeners or really anyone who appreciates having the slightest hint of green in their yard. And that giant shell, which can puncture car tires and breaks into biological shrapnel when hit with a lawn mower, isn’t going to build itself, so the snail devours any source of calcium it can find. Thus, in addition to ruining your tomato plants, the snail will turn around and lay siege to your house, gnawing off the calcium-rich stucco, which is made partially of lime, aka calcium oxide. And it even attacks concrete. If kept in captivity and not provided with enough calcium, it’ll eat the shell off another snail’s back. (For this the snail’s equipped with a tongue of sorts, known as a radula, which is packed with tiny, tough teeth. So the snail doesn’t so much chew up plants and houses as it does rasp them away bit by bit.)
The situation in Florida is dire, but i
t ain’t the state’s first rodeo with the invasive snail. Back in 1966, a family went on vacation in Hawaii and returned to Florida with a few extra members: The son smuggled back three giant snails and handed them over to his grandma, who released them in her backyard. The population exploded and spread. A decade later, officials had destroyed some eighteen thousand snails at a cost of a million bucks. The giant snails were vanquished—for the time being.
Fast-forward to September 2011: the Second Coming of the Snails. It was a Miami homeowner who first discovered them, and a mere six months later officials had collected forty thousand snails, more than twice what they’d found over the decade of the first invasion. Three years later, that figure had ballooned to 140,000. In fairness, the government has done a fine job reining the things in, keeping the giant snails mostly contained in the Miami-Dade area. They’ve mounted a huge public outreach campaign, complete with old-timey WANTED posters that bear photos of the pest and a hotline to report sightings, though it should be noted that they lack any mention of a REWARD. But reward notwithstanding, the campaign seems to be working, and it’s a good thing it is. At stake is billions of dollars’ worth of agriculture statewide. If the giant snails start radiating out of Miami-Dade, it’ll be a disaster. Pretty much everything is on their menu, including that famous Florida citrus we’re all so fond of.
FIRST STOP: SNAILS. NEXT STOP: CHEAP PARTICLEBOARD FURNITURE
The giant African land snail may not have predators in Florida, but in Brazil, a bird called the great antshrike has struck on a novel way to control the invasive species: It grabs the juvenile snails and carries them back to its favorite rock and repeatedly smashes them against it. It’s a fascinating case of tool use among birds (crows have been known to use much bigger tools for cracking open food, placing walnuts in the middle of the road for cars to run over), and it’s pretty impressive, if you ask me. I mean, I’ve got a great big human brain and I still struggle to build IKEA furniture, even with those nice little illustrations in the instructions.
I can tell you who’s not helping: folks who are fond of certain rituals, and who may have been responsible for Florida’s Second Coming of the Snails in the first place. A man allegedly smuggled the snails in and raised them in a box in his backyard, before slicing them open while they were still alive and pouring their bodily juices into his followers’ mouths. The expected ensued. His loyal subjects fell violently ill, “losing weight and developing strange lumps in their bellies,” according to the Miami Herald. But they could have had it much worse. The giant African land snail carries the dreaded rat lungworm, which infiltrates your brain, paralyzing or blinding or even killing you.
Thus are the exploits of the giant African land snail, coveted by a few goofballs and dreaded by just about everyone else.
Aye-Aye
PROBLEM: Grubs are packed with protein. But the thing is, grubs can pack themselves into the safety of a tree branch.
SOLUTION: A haunting lemur called the aye-aye develops beaverlike teeth to gnaw into the wood, plus a freakishly long finger to fish out grubs.
Eight months before Darwin published On the Origin of Species, the famous English anatomist and accomplished curmudgeon Richard Owen got a letter from a countryman posted as colonial secretary on the island of Mauritius. Before he’d left England, the secretary promised to send Owen any interesting specimens of natural history, and he was now writing to say he had a doozy from the neighboring island of Madagascar: an aye-aye, named after the natives’ cries of astonishment when glimpsing one. It was a bizarre kind of lemur, about the size of a cat, with huge ears, “teeth as large as those of a young Beaver,” and a middle finger “being slender and long, half the thickness of the other fingers, and resembling a piece of bent wire.” The secretary added with a nudge-nudge-I-really-went-out-of-my-way-for-you that “the Aye-aye is an object of veneration at Madagascar, and that if any native touches one, he is sure to die within the year; hence the difficulty of obtaining a specimen. I overcame this scruple by a reward of £10.” Nudge nudge.
The secretary put the aye-aye in a wooden cage and dropped in some tree branches bored through with grubs. These interested the aye-aye. The creature examined the branches, bent its big ears toward them, and “rapidly tapped the surface with the curious second digit, as a Woodpecker taps a tree, though with much less noise, from time to time inserting the end of the slender finger into the worm-holes as a surgeon would a probe.” It was tapping to agitate the grubs, and listening for the resulting movement. The worms would retreat deeper into their burrows, but eventually the aye-aye succeeded in catching them, gnawing through the bark into a chamber and reaching in with that long, slender finger to haul out the prize.
On such a diet (supplemented with dates—for fiber, I guess?) the secretary was able to keep the aye-aye alive. But the animal eventually escaped, whether by gnawing through the wooden bars with its beaverlike teeth or some other means isn’t clear from the secretary’s letter. It was soon recaptured, though, and, per Owen’s instructions, “killed by chloroform, its arterial system injected, the cranial cavity exposed, the abdominal cavity and alimentary canal injected with alcohol, and the whole animal then immersed in a keg of colourless spirit.” The secretary then shipped it to Owen, who proceeded to do a seventy-page write-up on the anatomy of the Malagasy curiosity.
MIGHT AS WELL JUMP
Over on the islands of Southeast Asia, a different primate has modified its fingers for other means. The tarsier is a tiny nocturnal creature that would fit in the palm of your hand, but it’s a voracious hunter, bounding from branch to branch snagging insects. Its fingers are slim and elongated, much like the aye-aye’s, but topping each one is a fleshy pad that helps the tarsier stick landings. Which is just as well, because in addition to its modified hands, it has a highly elongated tarsus—the bones that make up the ankle and give the tarsier its name—that allows it to bound an incredible fifteen feet. That’s the equivalent of a six-foot-tall human leaping 180 feet. Doubt you’d be able to stick the landing, though.
Now, Owen has been cast as Darwin’s nemesis, a reactionary defender of Victorian ideals and a combative old man who loathed the idea of natural selection and above all else believed that a higher power had tailor-made every creature for its niche. And it probably hasn’t helped his reputation over the years that he really was a bit of an ass, or that the guy looked real sketchy, like the love child of the Wicked Witch of the West and Ebenezer Scrooge. (Conveniently enough, one of Darwin’s allies who publicly attacked Owen, Thomas Henry Huxley, branded him a “humbug.” Huxley got all up in Owen’s grill, so to speak, in a legendary meeting of scientists in which Owen claimed humans were distinct from gorillas, and therefore could not have descended from apes, because only human brains had a hippocampus—except that’s not strictly speaking true at all.) And it didn’t help that when Darwin published On the Origin of Species, Owen anonymously penned a scathing review, a stunt that Darwin chalked up to jealousy in his autobiography.
In fairness, though, Owen had his own vague, undeveloped evolutionary ideas, however much he savaged Darwin and his allies. And ironically enough, one of Owen’s greatest theories—which predated Darwin’s discovery of natural selection—lent huge insight into evolutionary theory. Owen realized that something like the aye-aye’s hand wasn’t just a modified primate hand, but a modified mammal hand, because a creator had used the same blueprint, which the cranky anatomist called an “archetype,” across all manner of creatures. He had discovered what Darwin later realized was a component of common descent, that an aye-aye hand is like a human hand because long ago we shared an ancestor that had such a thing. The aye-aye went one way and developed that elongated finger, while we settled on our more uniform digits.
THAT’S A BIT OF A STRETCH
Another debunked evolutionary theory of note is that of French naturalist Jean-Baptiste Lamarck, who prior to Darwin had argued that animals could acquire traits du
ring their lifetimes and pass said traits to their children. So giraffes got their long necks by stretching to reach the tops of trees, stimulating the concentration of a so-called nervous fluid to encourage growth. In reality, mutations that produced longer-necked giraffes allowed the creatures to exploit out-of-reach leaves, boosting their chance of survival and therefore their chance of passing along long-neck genes. But to his credit, Lamarck also posited that organs that creatures no longer have much use for fade away over time, which is entirely true, as in the case of the naked mole rat’s atrophied eyes.
But why? Well, the same forces that made the satanic leaf-tailed gecko so satanic and so leaf tailed. When Madagascar set out on its own, its ecosystem went into flux. In their isolation, the island’s animals have assumed any available niches—the aye-aye, for instance, taking on a role hunting wood-boring grubs, a role that would typically go to a woodpecker. (On the other side of the planet, in Barbados, another curiosity, called the threadsnake, has taken on an ant-hunting role that’d typically go to an invertebrate, a centipede maybe, shrinking so much over evolutionary time that it can now curl up on a quarter. That’s how powerful of a force isolation can be.) With its conspicuous lack of a beak to chisel away at tree branches, the aye-aye has had to make do with the modified tools of a primate: those dexterous fingers, and fused, rodentlike teeth so tough that aye-ayes in captivity have been able to chew through cinder blocks. How dexterous are those digits? The aye-aye’s middle finger actually has a ball-and-socket joint like a shoulder, allowing the digit to swivel around as it feels through the grubs’ chambers.