One of the weird things about studying the bi- and homo-sexuality of animals is realizing how much I don’t know about their hetero-sexual practices. Take squid for example. How do squid have sex?
It turns out male squid who live in the deep dark only occasionally swim past each other, and when they detect another hot little squiddy number cruising past…
…the male ejaculates a packet of sperm at the mating partner, and the packet turns inside out, essentially shooting the sperm contained in a membrane into the flesh of the partner, where they stay embedded until the female (if the shooter has been lucky) is ready to fertilize its eggs. (NYT)
Scientists in the Monterrey Bay Aquarium reviewed years of undersea videos of squid behavior and found 39 images where they could tell the sex of squid, 19 females and 20 males. Of these, 9 males and 10 females had embedded sperm. So what we learn is: squids shoot their sperm at all passing squid, male or female.
The scientific paper announcing these results, “A shot in the dark: same-sex sexual behavior in a deep-sea squid,” hints at a controversy within. Why does this happen? Scientists split on the motivation of same-sex sexuality in animals. Often, scientists assume that animals that have sex with the same-sex are just dumb, that squid, among others, cannot determine the sex of other squid. This explanation strains credulity and tears at the rationale for a procreative drive. Increasingly we understand that same-sex sexuality also serves a purpose, otherwise evolution would weed it out as wasteful misfires.
Why do male squid fire their sperm packets at other male squid? The question remains unanswered.
(FYI, calimari is just Italian for squid, but sounding more delicious, it is the more common name on restaurant menus, where you and I are most likely to run into it.)