Those Amazing Holothuridea

Okay, so I too want to jump on the recent sea cucumber mania "sweeping" the science blogs. It all started over on The Intersection with a post on some cool recent research that points to the hitherto lowly sea cuke as up-and-coming rock star marine organism for its ability to regenerate lost tissue and organs. Turns out that this nifty trick has plenty of implications for human benefit.

I also love sea cucumbers as cool exemplars of symbiosis. Some sea cucumbers have a commensal fish known as the Pearl fish (Carpus sp.) which lives inside their anus during the day and emerges at night to feed. When morning comes, it simply waits for the anus to open as the sea cucumber breathes (yes, sea cukes breathe through their vascularized butts), and swims back inside. Pearl fish are highly modified eel-like fishes which lack scales and pelvic fins. They live in the body cavities of sea cucumbers, giant clams and pearl oysters during the day, leaving at night to feed on small fishes and shrimp. Juvenile Pearl fish are parasitic, feeding upon the gonads of sea cucumbers.

I can't think of any terrestrial analogs for such a commensal relationship. Well, maybe just one.