ABSTRACT
The interior of the marine sponge, Damiriana hawaiiana, which is common on the tidal flats of Coconut Island, Kaneohe Bay, Hawaii, contains a variety of animals, most of which are commensal. The most important inhabitant is the six-armed ophiuroid, Ophiactis savignyi. Often, more than 20 specimens of different sizes fill the canal system. They obtain enough oxygen and nutrients from the water, that circulates through the sponge. Many egg-bearing specimens were found. Usually, the brittle stars form a tangled mass, limiting the movement of the individuals, and it seems that they remain for their entire lives in the host. They are part of a well protected benthic community adapted to the structure and activity of a large sessil animal. The relationship between the brittle star and its host is discussed.
