In many Antarctic benthic communities, sponges can be considered as keystone species on both hard and soft bottoms, affecting community structure and sediment texture (Cattaneo-Vietti et al. 2000). Moreover, Antarctic sponges are known to be exploited by numerous organisms as atrophic source. The most important Antarctic sponge predators are asteroids and molluscs which move and digest slowly. The activity of invertebrate predators is not affected by the sponge nutritional composition: toxicity and relative abundance are considered to be the most important factors regulating predation on the Antarctic sponge fauna (McClintock 1987).