Zebra Crab Macro Footage

The fauna of the “soft bottom habitats” or “muck diving” sites continues to fascinate. Seen in Dauin this week: A zebra crab living on a very venomous fire urchin, and a crinoid clingfish in-between the filter feeding arms of a crinoid. The crab is of course highly protected by the dangerous spines of the urchin, but is there an advantage of the pairing for the urchin?

The crab could fend off parasites, or it could serve as “eyes” of the urchin. I am not sure if anybody has entertained that possibility? The small crab might very well be able to manipulate the direction the urchin is going by pinching it in the right way, and while urchins are not blind, they don’t have the eyes and the visual system of a crustacean.

Alternatively, the crab might be a parasite of the urchin.

Check out the pair in the video for yourself, and let me know your thoughts (ideally as YouTube comments, I respond to these quickly).