Several years ago my son was watching a nature program on TV while I was doing housework. As I moved in and out of the living room, all I caught was an occasional sentence or two from the show, totally out of context; one of these, intoned in a portentous nature-show voice, was “But mating is a risky business.” Although I’m sure the show was not about humans, I had to agree. But if you think humans sometimes have it tough, consider the Australian cuttlefish.
The male/female ratio is drastically skewed, with as many as 10 males for every female. The big strong males can fight off competitors if they can persuade a female to mate with them, but the smaller guys try a smart trick instead. Cuttlefish are able to make astonishing changes in their appearance to disguise themselves from predators; on TV once I saw what looked like a video of some kind of plant sitting on the sea floor, until part of it seemed to turn into a cuttlefish and swim off. Even after the video sequence was replayed, I couldn’t believe my eyes. So a small male cuttlefish transforms himself into what looks like a female, so he can sneak past a larger male and get close to the female that the bigger fish is guarding. The big fish doesn’t chase him off, because presumably he appreciates having another female, but the smaller male then has a chance to mate with the real female.
The really surprising thing is that the females prefer these guys, being more likely to mate with them and, more to the point, let their eggs be fertilized by them. I’ve wondered about the brains of cuttlefish; I saw the video of that magical transformation on a show about looking for intelligent life elsewhere in the galaxy, and the point was that there are plenty of complex brains down here that would never be apparent to anyone on another planet; some of them are barely known to those of us who live on this one. The cuttlefish have some huge number of chromatophores that change color and size to allow them to make dramatic changes in appearance, and their brains, the processors that control all of the chromatophores, have to be fairly large and sophisticated. I don’t want to anthropomorphize these female cuttlefish and cheer them on for choosing wit over brute force, but it is a cool story anyway. (And as I recall, the reason the cuttlefish have this elaborate system of mimicry in the first place is that they have few other defenses; their success against predators lies in craft rather than force. That’s one reason I find them so interesting.) The only down side for the small males is that sometimes they look so convincingly female that a larger male will try to mate with them. Nobody said it would be easy. After all, mating is a risky business.
You can learn more about cuttlefish and other cephalopods at the Cephalopod Page.
