Individual Ophiothrix lineata live inside the tubes of the sponge Callyspongia vaginalis.
The sponge is unique compared to most sponges on Caribbean coral reefs in that it broods larvae inside it’s tissue and releases them all year round. The size of these larvae, ~0.5-1.5 mm in length, are within the size range of potential food items for O. lineata.
So the question arises… can O. lineata consume sponge larvae?
To address this question, we placed individual brittlestars in a clear dish with seawater and some sponge larvae. The video was shot in the dark, using infrared lighting, as brittlestars do not like the light. The camera is pointed through the clear dish at the the oral surface (mouth) of the brittlestar.
Watch the video below, and see just what the brittlestar can do. You can see the motile larvae swimming around in the dish, and the brittlestar using it’s tube feet to capture and consume the larvae.
Read more about these experiments in the recently published work:
Henkel, T.P. and Pawlik, J.R. 2014. Cleaning mutualist or parasite? Classifying the association between the brittlestar Ophiothrix lineata and the Caribbean reef sponge Callyspongia vaginalis. Journal of Experimental Marine Biology and Ecology. 454:42-48.