About Amphimedon compressa Duchassaing & Michelotti, 1864
Amphimedon compressa can reach 40 cm (16 in) in length and 4 cm (1.6 in) in diameter, though individuals growing in shallow water are typically smaller. Tree-like curved branches develop from a basal encrusting mass, but very rarely, this sponge may grow as a small, unbranched, flattened hemisphere. Many small osculi are present on its branches. Its color is most often a dull dark red, but it varies, and may sometimes be black, dark brown, greyish-brown, bright red, or orange. In dark locations under overhangs, this sponge grows in mats and has a pale, weak coloration.
Commonly called the erect rope sponge, Amphimedon compressa is a member of coral reef communities. It is found in Florida, the Caribbean Sea, and the Bahamas, at depths down to approximately 20 m (66 ft). It grows on rock on reef crests and sides, and on vertical rock surfaces it protrudes sideways. Off the Cayman Islands, Amphimedon compressa forms part of a sponge community in a belt at depths between 80 and 240 m (260 and 790 ft), where it often grows horizontally outward from rock faces. The sponge brittle star Ophiothrix suensoni frequently lives on the surface of this sponge. While sponges are commonly eaten by sea stars, Amphimedon compressa produces specific secondary metabolites that discourage feeding by the common Caribbean starfish Echinaster echinophorus.
