Green Island Hammerhead Trip (Feb11) C 190.jpg
Big Mushroom, Green Island - Upside-down diver over a sea cucumber, Bohadschia argus.
Like many holothurians (sea cucumbers), B. argus can extrude sticky defense threads, the so-called Cuvierian tubules.
A little-known fact is that a commensal fish, a Carapus sp., lives inside the anus (!) of this sea cucumber and forms a symbiotic relationship with it.