How They Do It

OK, so you haven't spent sleepless hours trying to figure out how sea stars or octopus or potato bugs make babies. But contemplate now the weirdly wonderful world of sex among the wiggly, squishy, crunchy, often faceless creatures that make up most of the animal kingdom.

And I'm talking sexual reproduction, not asexual. Big difference. Simply put, throughout the living world as we know it, sexual reproduction is the union of egg and sperm. Period. Sex, though, is only one form of reproduction. Cloning, budding, splitting, and such gruesome-sounding activities as pedal laceration, are asexual forms of reproduction that take place without the union of egg and sperm.

The complexities of sexual reproduction, especially with animals that lack obvious organs such as penises or vaginas, is what I want to introduce today. The sea star (AKA starfish) for instance, is among the lucky animals that practice *pretty safe sex. No female or male parts collude in lustful embraces. No touching at all. Mature females release eggs into surrounding sea water and males release sperm into the same environment. Sometimes boys go first, sometimes girls. Often one animal's release triggers others nearby, turning the waters into a veritable soup of gametes. If the animals are close enough and the currents work in their favor, egg and sperm will meet, resulting in tiny larvae that will usually join the throng of multi-species plankton that is the basis for most of the marine food-webs.

There is definitely nothing safe about octopus sex. If you want the details (and they are amazing) let me know and that will be my next blog.

*At least one species of NW sea star, the mottled star, Evasterias troschelii, is often invaded by a parasite which causes no visible damage until the sea star spawns. Sea stars expend a lot of energy spawning and are often weakened afterwards, which is when Evasterias's parasite attacks, causing the sea star to literally fall apart and die.