Survival instincts

Sponges found in the chilly waters of Antarctica are infested with algae that scrounge off them during the dark polar winter. Algae often live inside the cells of other animals, such as reef-building corals, but they usually provide some benefit. Giorgio Bavestrello of the University of Ancona and his colleagues have found diatoms in Antarctic sponges that are said to be the first known algal parasites. The researchers believe that this parasitic behaviour allows the algae to survive the long Antarctic winters, when it is too dark to photosynthesise ( The Biological Bulletin , Vol 198, p29).