The Mystery of Solenodon, the Mammal That Bites Like a Snake

You’re a mammal, so pat yourself on the back—no, not you, lizard people from outer space posing as high-ranking members of the US government. Mammals have got it made: Fur to keep you warm, milk to nourish your young, relatively big brains to keep you not dumb.

What you don’t have, though, is a venomous bite … unless you are in fact a lizard person from outer space. Or, better yet, a mysterious mammal called the solenodon. They’re one of just a handful of mammals with venom glands that deliver a powerful toxin. But wait, there’s more: The solenodon’s nose has a ball-and-socket joint like the human hip, making it crazy flexible. And a lady solenodon’s teats are … oddly placed. Let’s just leave it at that for now.

If you find yourself in the forests of Cuba or Hispaniola, take a deep breath. It might smell kind of like a goat: musky, earthy, maybe a bit like wet dog, definitely pungent. Now look at your feet. You might find strange conical holes in the dirt, with scratch marks ringing the edges.

Chances are you’re not far behind the aromatic wonder that is the solenodon. Foraging typically at night, it jams its long, highly mobile ball-and-socket schnoz into the soil to root around for invertebrates, things like worms and insects. Its many sensitive whiskers help it feel around the dirt, which is just as well because the solenodon ain’t got much going on in the eyesight department.

“They’ve got tiny little eyes and they don’t seem to have particularly good vision, although they’re really sensitive to light,” says ecologist Joe Nunez-Mino. While not many solenodons live in captivity, the ones Nunez-Mino has come across run like hell if you switch a light on. Clearly, this is an animal most comfortable dancing in the dark.

But should you be lucky enough to bump into a solenodon in the wild, you’re in for a treat. Mildly put, this is a singular mammal. It’s about as big as a large rat with a tail to match. (Looks kind of like a Rodent of Unusual Size, don’t it?) It’s got long, sharp nails and ambles with a wobbly, I’m-just-coming-off-anesthesia gait. Females with their young are particularly awkward. “The teats are sort of in the armpit of the rear legs, and sometimes the females will kind of run around dragging the babies,” Nunez-Mino says.

An adult solenodon at right with a juvenile at left. Between them are rocks of indeterminate age.

All laughing at the expense of the solenodon aside, please no touchy this animal if you happen to find one. Not just because solenodon is endangered, but because it has a venomous bite, an extreme rarity for a mammal. (Shrews have a venomous bite too, and male platypuses have venomous spurs on their hind legs, though the males only use these to fight each other.) Sitting underneath the solenodon’s lower incisors are salivary glands that send venom along grooves in its teeth. All the solenodon has to do is break the victim’s skin—or cuticle, in the case of insects—for the venom to get in there and work its magic.

From the few reports of human envenomations, it sounds like the experience is no picnic. Symptoms are similar to a snake bite, including localized swelling and severe pain, perhaps lasting several days. (Ask your doctor if solenodon venom is right for you!)

If you’re lucky, though, you’ll get what’s known as a dry bite—that is, the critter will nip you without producing venom. And that makes good sense from an energy perspective. Snakes know what’s up here: “Snakes quite often will bite and not inject venom because using venom is actually quite wasteful unless you really have to,” says Nunez-Mino.

Check out the solenodon’s tiny eyes. It’s pretty much the Howard Moon of the forest.

Even if you do get a dose of solenodon venom, you’re getting off easy. The venom incapacitates other victims like lizards, and in laboratory tests, scientists dosed mice with the venom and recorded breathing problems, convulsions, and paralysis. And the solenodon doesn’t stop at prey smaller than it. “There’s one report of a solenodon kept in captivity in London that ate an entire chicken,” says molecular biologist Rodrigo Ligabue Braun of Brazil’s Federal University of Rio Grande do Sul. “He bit a chicken and then ate all the parts he wanted.”

If the also-venomous shrews are any indication, the solenodon may not always be killing and consuming its prey outright. Shrews will often bite and incapacitate their victims, then drag them to their dens and come back later and gnaw on the comatose things. The solenodon may well do the same. (Oh relax—it’s not that bad in the grand scheme of things. The tarantula hawk is a wasp that stings, well, tarantulas, then drags them back to a den for its larva to devour it alive over the course of several weeks.)

Now the why. Why would the solenodon evolve venomousness while pretty much every mammal on Earth gets along fine without it? Well, it may not be the case of the solenodon evolving venomousness, as much as other mammals losing it.

Mammals have it made right now. But for tens of millions of years, puny little mammals spent the bulk of their time running away from dinosaurs. Many ancient mammals may have enlisted venom so they could better defend themselves.

But the game changed big time when the dinosaurs died out. “From an evolutionary point of view,” says Braun, “you’d be expending too much of your resources producing venom in an environment that did not have the same kind of prey or predators that it had before.” So it might have made sense for mammal lineages to evolve away from venomousness.

For whatever reason, though, solenodon held onto it. Indeed, solenodon is a truly ancient mammal, having diverged some 76 million years ago—not long (in evolutionary time, that is) before the dinos met their match in the form of an asteroid punching Earth right in the face. (Braun notes, though, that debate still swirls around the evolution of venom in mammals. It may be that venomousness was rare in early mammals, as it is today, and solenodon has just always been an oddity.)

While venom can land solenodon a meal and protect it from its natural enemies, it won’t do a lick of good against humans. Habitat destruction on Cuba and Hispaniola has hit the solenodon hard. Add to that the invasive species that humans have brought along and you’ve got a massacre.

Dogs in particular are a problem on Hispaniola, “although we’ve also recorded or heard of cases where the solenodon has bitten a dog and the dog has died from presumably the venom,” Nunez-Mino says. Feral cats, too, aren’t just a potential executioner, but competition: The felines target the lizards and large insects and such that the solenodon relies on to survive.

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