As scientists delve deeper beneath the ocean’s surface, they find bizarre creatures that have adapted to harsh and extreme environments. Now comes a new one–the discovery of the first multi-cellular animals that survive and reproduce entirely without oxygen. [Roberto Danovaro et al, BMC Biology , http://bit.ly/dcICgo ]
Researchers had thought that only single-celled organisms such as prokaryotes and protozoa could live in the oxygen-deprived environments of the deepest ocean. When scientists did find multi-cellular organisms, they assumed that they’d sunk from oxygen-enriched waters.