Mieke sent me this lovely photo of Australian nudibranchs a while back. My first thought was, “OMG! Koosh balls of the sea!” My second thought was, “They are TOTALLY doin’ it!” (See the loop of orange eggs in the upper right?)
Nudibranchs are sea slugs – just like land slugs, they are molluscs that have lost their shells. Since they don’t have any hard parts to protect them, they tend to be incredibly poisonous – they are pretty and colorful to advertise DO NOT WANT. Nudibranchs’ chemical defenses are usually stolen from their prey, the toxic compounds or stinging cells serving to protect the nudibranch long after that unfortunate sponge or anemone is but a tasty memory.
Like the mighty banana slug, nudibranchs are simultaneous hermaphrodites and can both fertilize and be fertilized. They can be tender, stroking each other’s tentacles, or debauched, mating in chains (who wants to be in the middle?) or snacking on their partner. (Apparently, unlike their banana slug relatives, nudibranchs do not engage in apophallation. Aren’t you disappointed?) Sadly, the sexy time comes at quite a high cost – most nudibranchs are semelparous, meaning they die shortly after mating.
With the help of Sea Slug Forum and Nudibranchs of Australia, I think Mieke’s nudibranchs in flagrante delicto are a species of Okenia, possibly Okenia stellata. Want more nudibranchs? National Geographic has stunning photos, videos, and even nudibranch puzzles.