It is widely distributed around the shores of the British Isles especially the western coasts. Habitat S. ficus is found growing on rocks from the lower shore down to a depth of two hundred metres and prefers locations with strong tidal flows. It often grows among seaweed and is also found on harbour structures and wreckage. When it grows on a stone or an empty gastropod or bivalve shell it may completely engulf it. It sometimes grows on a shell housing a living hermit crab. Biology Members of this genus are generally hermaphrodites. The male and female gametes may not be released simultaneously and sperm may be drawn into the vascular system of another individual. Fertilisation is internal and the ciliated larvae are liberated into the water column and become part of the zooplankton. Asexual reproduction also takes place, either by budding or through the development of gemmules. These are "survival pods" and remain dormant under normal conditions. They can become active when a period of adverse conditions such as an excessive exposure to low temperatures comes to an end. Ecology S. ficus does not have many predators. This may be because it has an unpleasant odour or because the spicules make it unpalatable. It is eaten however by some marine gastropods and some nudibranchs. It forms part of the diet of the Atlantic bluefin tuna (Thunnus thynnus). When the sponge grows on a shell occupied by a hermit crab there may be mutual advantages to both. The sponge benefits from the crab's ability to move away from predators such as nudibranchs, while the crab may benefit from the sponge's unpalatability and the camouflage it provides. S. ficus ssp rubrus is being investigated as a possible source of antibiotics, anti-fouling and other biologically active compounds because it was noticed that when the shells of cultivated scallops, family Pectinidae, were host to this sponge, no other invertebrates fouled the shells. References Bibliography Dangeard, P. (1932). Sur un Microspora symbiotique d'une éponge, Ficulina ficus (M. ficulinae sp. nov.). Bulletin de la Société Botanique de France, 79(3), 491–494. Suberitidae Animals described in 1842