By Philip Bethge
Sex in the deep sea is a difficult proposition. The problems already begin with the partner search: How do you find someone to mate with in the pitch-black depths of the ocean? And for any creature that does manage to have a rendezvous beneath the waves, failure is simply not an option.
"Seize the moment," is how Dutch researcher Hendrik Jan Ties Hoving describes the most basic rule of undersea reproduction. "Chances are low of finding a partner a second time."
The array of techniques is impressive, Hoving says, but also takes some getting used to. His conclusion: "Reproduction is no fun if you're a squid."
Most of the squid behaviors that have come to light so far are striking and bizarre. For example, researchers in California photographed one species, Gonatus onyx, caring for its brood. This squid, which measures just under half a meter (one and a half feet) long and lives in water around 2,500 meters (8,000 feet) deep, stretched its arms into a kind of web, holding a gelatinous matrix containing 2,000 to 3,000 eggs. It regularly flushed fresh water through this egg mass, presumably to aerate the embryos.
Now Hoving has unveiled what seems like an entire Kama Sutra of the squid world. The subjects of his study were all already dead at the time he observed them, but what the biologist found in museums, obtained from fishermen and collected from the ocean on scientific expeditions off the coast of Namibia and the Falkland Islands is nonetheless sensational:
Hoving has an explanation for this strange avoidance of bodily contact: "Mating is probably quite risky for the male," he says. "In most species they're smaller, and could get eaten."
He has a similar explanation for the males' rough behavior: "More than anything, it's about being fast." It seems the males are quite literally under great pressure. A few years ago, Australian biologists discovered sperm packets under the skin of a freshly caught 15-meter (50-foot) female giant squid. Covered with a "gelatinous" substance, they had presumably been "injected" by a male, the researchers reported, "under hydraulic pressure," with a penis "up to 92 centimeters (three feet) long."
Small wonder that things sometimes go wrong. Hoving discovered sperm packets, among other places, in the eyes of animals he studied. And one giant squid found off the coast of Norway seems to be a not atypical case: a male, it also had spermatophores under its skin. The science journal Nature offered the interpretation that the squid may have "literally shot itself in the foot."
In the end, however, it seems fertilization does manage to take place in most cases. Squid are certainly numerous enough -- according to Hoving, there are around 200 species in the deep ocean. Not even overfishing does harm to them, he says. Quite the opposite, in fact: "The squid have more to eat, since they don't have to share their food with the fish that are caught for consumption."
A female squid releases millions of tiny eggs into the water, but generally only once in her lifetime. When she does, the sperm stored under her skin are discharged simultaneously. The father for this legion of embryos is often the single male who got his beak or hooks on the female first.
Thus the brutal attacks by some male squid have another purpose, Hoving believes. "The females have downright negative experiences with mating, meaning that afterwards they won't let any other male near them."
It's a forced fidelity for the squid, and Hoving even has a technical term ready for it: "traumatic insemination."
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