Clusters of open tubes on rubble slopes, and a reliable place to find shrimps and gobies.
A sponge growing as clusters of upright open tubes, usually blue-grey, purple, lavender or cream, with a fine mesh texture on the outer surface and a smooth interior. Individual tubes reach about 60 cm. Several species occur and are not separable underwater; this entry covers the genus.
Water is drawn through the tube wall and expelled from the open end. The interior of a tube is a sheltered, current-fed space and is worth looking into: cleaner shrimps, gobies, brittle stars and juvenile fish use it, and on muck sites a stand of tube sponges on otherwise open rubble is one of the few pieces of structure for some distance. Sponges are chemically defended and are eaten by comparatively few animals — angelfish, some butterflyfish, hawksbill turtles and a number of nudibranchs. Recorded from about 3 to 40 m.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
