Category Archives: Insectivores

The Subterraneans

Underground! From rabbit warrens to nuclear fallout shelters, it’s a great place to hide out. If you’re a terrestrial vertebrate, the safest place you could conceivably be is underground, where you’re protected by a temperature-stable bunker, an ocean of dirt, rocks, and roots. But it’s one thing to dig a burrow, and another to spend all your time underground, swimming through the soil. If you’re a full-time tunneler, there are really just two body types you can evolve to fit: the “mole” model, and the “earthworm” model.

Consider the difficulties of underground travel. You don’t want to be too large, or digging would be exhausting. You don’t want large eyes, which would be useless and become full of grit. You’ll need a keen sense of smell and touch, as you’re likely to be finding food by chemical and tactile signals rather than visual ones. This star-nosed mole from North America is a great example of the mole archetype: small, compact, wedge-shaped, with sealed-off eyes and ears, powerful front claws, and 22 fleshy appendages that are among the most sensitive touch receptors in the animal kingdom. Star-nosed moles are true swimmers; they breaststroke through soil, but are also quite adept at catching prey in the water. Moles are insectivores, related to that most ancient of mammals, the shrew. But thanks to the awesome power of convergent evolution, you don’t have to be related to the moles to become a mole.

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Finally. The one you’ve been waiting for.

The list of bizarre sexual rites in the animal kingdom is almost too numerous and well-documented to enumerate. Even if I were to define “lust” by the quantity of sex a species has, as opposed to just the quality, I’d be writing until you fell out of your chair, stunned by the sheer depravity and shocking variety taking place in the name of sexual selection. For example, lions in heat will mate 20-40 times a day for several days in a row, and the male lion’s corkscrew-shaped penis has backwards-facing barbs which both help him stay attached and rake the vagina to induce estrus. A pig’s orgasm can last half an hour. And how do porcupines make love? Very carefully… and also insatiably, as the female is only in heat for 8-12 hours a year. With only a half-day window of opportunity, the female will mate with a lover until he is exhausted, and then move right on to the next. Conjugal visits begin with foreplay which involves the male hosing the female with urine from six feet away.

My natural pick for an animal to represent “lust” would be the bonobo, a chimp-like ape which uses constant sex as a means of social bonding. However, since I’ve already written about the bonobo in another context, I’ll have to choose something new. Reproduction being essential for life, it’s hard to define “lust” as an over-indulgence in the animal kingdom; animals that procreate often are just fulfilling their biological imperative. But there are a few cases so exceptionally naughty, so blue, so indisputably NSFW that I am forced to admit that, when it comes to the dirty deed, Homo sapiens is a total prude.

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Drunken Monkeys!

Good morning, sunshine. Or is it afternoon already? Did you have fun last night? How’s your head? Yep, you know you’re not supposed to mix tequila with Kahlua. I’m going to take advantage of this excruciatingly bright day in New Mexico to discuss a subject close to my heart, my aching brain, and my liver: Alcohol tolerance and abuse in the animal kingdom.

One of the many great things about booze is that it occurs naturally in the wild. Fermentation, the process by which a yeast transforms sugar into alcohol (and its by-product, carbon dioxide), needs no brewmaster or whiskey still. Yeast is blowing freely in the wind, and wild grapes were turning to wine long before we were cultivating chardonnay. Nutritionally speaking, alcohol is a double-edged sword: it’s extremely energy-rich, but it’s also toxic and makes you fall down. So it makes sense that animals which eat fruit would develop a tolerance to alcohol, gaining its energy while avoiding getting so drunk that they start hitting on their predators at the bar. (Or, if you’re a fruit bat, flying into a tree.) And the tolerance these animals have for liquor would put the most gin-blossomed tippler to shame.

Meet the greatest drinker in the world: the pen-tailed tree shrew. This tiny, unassuming nocturne from the rainforests of Southeast Asia may not look like a heavyweight, but pound-for-pound, it could drink you under the table. After all, it subsists entirely on a diet of palm nectar which is fermented by wild yeast to a fine 3.8 alcohol content. To mimic the tree shrew, you’d have to survive on only beer for your entire life. (Which is technically possible, I’ve heard from a bartender friend, but not recommended.) Despite consuming what would be, for us, the equivalent of nine glasses of wine a day, and having a blood alcohol level that is constantly above any country’s legal limit, the tree shrew remains sober. How it metabolizes its alcohol so efficiently is still a mystery, but scientists believe that the answer, when found, could present us with a cure for alcohol poisoning, and perhaps a weapon against alcoholism. Right now, most alcohol research is done on lab rats, and rodents tend to avoid alcohol by preference. But the tree shrew actually resembles the earliest primates on a taxonomic level, and could give us insight into our own alcohol tolerance and predilections. What’s more, we’re not the only primates out there that like to hit the sauce.

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I like to start each day by drinking a nice hot mug of cobra venom.

Did I say cobra venom? I meant coffee. But if I wanted to, I could certainly drink cobra venom, provided I didn’t have any cuts in my mouth or esophagus. I offer this as an example of one of the many ways that “venom” is not synonymous with “poison.” A poison can be anything that harms the body, from complex organic compounds to heavy metals to atomic radiation to bleach under the kitchen sink. But venom is special. Venom is an arrangement of proteins and enzymes that must be injected into a victim’s bloodstream through a mechanical device, such as a fang. Poisons are land mines that anyone can step on; venoms are delivered special to you.

Most of the venomous animals in the world are snakes, but there are a fair number of fish and lizards that deal death as well. The stonefish, the world’s most venomous fish, uses spines to defend itself against attackers, and can certainly kill a human, and gila monsters, one of two North American venomous lizards, produce a neurotoxin which cause an excruciatingly painful paralysis. The world’s most venomous land snake, Australia’s Inland Taipan, has never killed a human due to its reclusiveness, but the venom in one bite is powerful enough to kill 100 people. A few molluscs make the list: the golf ball-sized blue-ringed octopus — again, Australian — has a blinding, paralyzing toxin that will kill a human victim in minutes, and for which there is no antivenin. The venom is nearly identical to that of the marbled cone snail, nicknamed the “cigarette snail” because you’ve got about enough time left on Earth for one cigarette after it stabs you with its neurotoxin-tipped harpoon. But the most venomous animal in the world is the infamous box jelly, the “suckerpunch of the sea,” a nearly-invisible predator responsible for over 5,500 human deaths since 1954. Of course, its fatal deathblow usually comes from the drowning triggered by extreme pain before the venom can stop the victim’s heart.

Clearly, venoms are useful to predators across the animal kingdom: reptiles, fish, insects, cnidarians, molluscs, and even a few amphibians. Why, then, aren’t more animals venomous? And why aren’t there any venomous mammals? And here is where a few of you zoophiles say, What about the duck-billed platypus? Very good; just testing you. The male duckbilled platypus, and only the male, has venomous spurs on its hind legs. The few other venomous mammals are all types of shrew, including one of the rarest and strangest: the solenodon.

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You know what’s been on my mind lately? Midgets. Well, dwarfs. Well, actually, pygmies. I’ve been considering a post about pygmy animals for a while, and as luck would have it, a research team in Borneo just found this miniscule marvel:

Yes, that’s an adult frog. (If it weren’t, it’d be a tadpole, silly.) Measuring only 12 mm, the male Microhyla nepenthicola is the smallest frog in Europe, Africa, or Asia — though, amazingly, there are two species in the Americas that are even tinier. M. nepenthicola‘s species name comes from the Nepenthes pitcher plants it inhabits to keep its skin wet. It might never have been found if it weren’t for its loud, rasping call, which conjures for me an image of a puzzled biologist putting his ear to a pitcher plant like a dog to a Victrola gramophone, wondering why it was croaking.

As megafauna ourselves, I think most humans have this idea that species are trying to evolve to be larger, but are somehow limited. But the fact is that being small has its advantages, and many species are more than willing to become miniaturized to seize the opportunities that can only be found once you breach the microcosmos.

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