This Critter Definitely Doesn’t Have a Penis on Its Head

The elephant fish chimaera and its characteristic snout. No, that's not what I'm talking about with the penis stuff. That's another structure entirely. I mean, that there would be a weird-looking penis.

If the ancient Greeks loved anything, it was mashing up different creatures into nasty mythological beasts. (Well, that and columns. Boy, they sure loved their columns.) And perhaps the most bizarre among them—the beasts, not the columns—was the chimera. It had the body and head of a lion, a tail made of a snake, and, somewhat inexplicably, a goat head sprouting out of its back. And it breathed fire.

Well, it turns out there are real-life chimeras—at least in name anyway—that may be even stranger, on account of actually being real. Only these are called chimaeras, and they don’t breathe fire, largely due to the fact that they live in water. And while superficially chimaeras resemble sharks, they’re only a distantly related, ancient species, having appeared some 400 million years ago. These are truly some of the most enigmatic and unique fishes of the deep sea. Oh, also, they don’t have penises on their heads, contrary to what you may have heard.

One of the few people who knows a damn thing about the mysterious chimaeras is evolutionary biologist Douglas Long of St. Mary’s College in Moraga, California. The problem, he says, is that these things usually live too deep to get caught in fishing nets (well, I guess that’s actually a good thing), and it’s not like humans are spending a tremendous amount of time sending submersibles down there. But we can make our best conjectures, and we’ll start with the remarkable snouts of the so-called rhinochimaeras.

Like sharks, chimaeras probably hunt down their food by following the trail of electricity emitted when creatures move their muscles. “As they’re swimming above the substrate, it’s believed that they can somehow detect buried invertebrates that are under the sediment, or sticking out of the sediment,” says Long. “Then they sort of dive in and take them out.” Nobody’s actually seen this happen, he notes, but the chimaera’s snout is packed with nerves and structures for electrosensory perception. And while it’s likely that all chimaeras have this ability, the rhinochimaeras—one of which you can see meandering below—could have adapted to supercharge this power with their formidable schnozzes, utilizing more surface area to pack in more sensors.

An incredible rhinochimaera looks a bit like Dumbo. Only those are fins, not ears. And that isn’t technically a nose. But whatever.

The thing is, life is exceedingly scarce in the deep, and if it helps you eat, a big nose is nothing to sneeze at. [Editor’s note: Ugh. Seriously? Fine.] And if you can be a more generalist hunter on top of that, all the better. From what little we know of their diet, there doesn’t seem to be much chimaeras pass up: They’re hunting everything from soft invertebrates like worms on up to hard-shelled bivalves. And for this they’re equipped with rather remarkable mouths. Unlike sharks, which continuously lose and replace their teeth, chimaeras have beak-like chompers. That setup lets them crush hard-shelled critters as well as hoover up squishier fare. And as the beak wears away after repeated gnashing, it continuously grows back.

Chimaeras of course have their own predators. For those, they come prepared with a defensive spine at the base of their dorsal fin—one that, in at least some species, can deliver toxins. Exactly how that toxin is delivered isn’t quite clear yet, according to Long. The chimaera known as the Pacific ratfish, for instance, doesn’t seem to have an obvious venom gland. That means it may not deliver venom like a rattlesnake, with its needle-like fangs. Instead, it might be more of a toxic slime that coats the chimaera’s spine, like stingrays do it (also, FYI, one of the largest freshwater fishes in the world, the 16-foot giant stingray, sports a stinger that’s 15 inches long). In the rhinochimaeras, it may be that the spine isn’t toxic at all, and is just meant to inflict good old trauma.

For the Last Time, Chimaeras Do Not Have Penises on Their Heads

The vast majority of fish have this funny habit: When a girl fish and a boy fish love each other very much, they just dump their gametes into the ocean. With any luck, the two will mix and make babies. But not sharks and chimaeras—they’re internal fertilizers. And internal fertilization can be a bit difficult if you don’t have limbs to help you grasp your partner.

Male sharks have highly modified fins known as claspers (those two dangling bits you see on great whites, for instance), which they insert into females to deliver sperm. “One of the issues is that you need to get some leverage to be able to insert this into the female,” says Long. “And so with sharks and rays the males will frequently bite onto the females, bite onto the fin or even bite onto the body so they can get leverage and slip that clasper in.”

Male chimaeras have these claspers as well, but they’re also equipped with a specialized club-like structure on their heads. This is covered in small hooks, and is thought to help the male hold onto the female, though no one has ever seen this in action to confirm it. “And the problem that I’ve had with people is that they’ve said, ‘Oh, it’s the shark that has a sex organ on the head,’” says Long. “And somebody will write another article saying ‘the shark with the penis on the head.’” Well, sir, that stops right here.

First of all, it’s not a shark. And second, while the structure is probably helping the chimaera fertilize the female, it’s definitely not a penis. Sharks and chimaeras don’t even technically have penises in the first place. “But it is involved in copulation, the same way that your arms are when you’re with your significant whoever, holding them close and hopefully being a little more successful by using your arms rather than not using your arms.” (While I declared a few weeks ago that science’s greatest analogy ever was a researcher telling me that a female octopus wringing out a male’s disembodied, sperm-packed arm onto her eggs was like squirting soy sauce onto rice, Long’s analogy here is a close second.)

Now, while some mother sharks lay eggs, others will allow the young to develop inside themselves and emerge relatively developed. Chimaeras, though, have a rather more peculiar way of going about things: Females drag a pair of eggs along with them by a tendril. “She’ll lay the eggs, but that little tendril will still be in her cloaca,” says Long. “She’ll be swimming around dragging the two eggs behind her, and some people think that might actually be a form of what’s called egg guarding.” Instead of dropping her eggs on the seafloor and leaving them to the mercy of predation, she just totes them along. Then again, Long cautions that it may be that she just takes her sweet time laying them, and that they eventually do drop and settle on the seafloor.

Read more at Wired Science