Last week I wrote about the echinoderms, the spiny-skinned-animals. We learned about their tube feet, a hydraulic system unique in the animal kingdom. But there are even more amazing appendages on the skins of these animals!
Seastars and sea urchins also possess claspers, called pedicellariae by scientists. Like the tube feet we discussed in the last blog post, these are working semi-independently. Each clasper has its own small nervous system, and decides relatively independently where to turn and what to grasp. A set of clever rules makes sure that what each clasper does serves the common good of the whole animal.
If you look at the extreme close-ups in this video, you can see the claspers in action:
These are microscopic images from a very interesting study by Simon E. Coppard and colleagues. What beautiful tiny structures! Some of them are fragile, evolved to scrape of bacterial films from the skin of the urchin. Others are more sturdy, and specialized to remove parasites from the animal’s body surface. Yet others are venomous, and inject that venom with structures akin to tiny hypodermic needles into an attacking predator.
So, the next time you see a seastar, don’t just think of it as another rather common marine animal you encounter on your search for the really rare critters in Dauin. Think of all the amazing things this only superficially slow and boring animal can do with its skin. If you see a sea urchin, don’t just think of it as a dangerous nuisance capable of painfully poking you. Think about the animal’s skin contains a battery of hydraulically-powered feet, and a whole selection of tiny claspers, each specialized for different tasks.
I find that the more I learn about the ocean, the more interesting each single dive becomes. Even encountering a rather common sea urchin turns into a fascinating encounter with an animal with a skin with truly outstanding capabilities.