Brittle-star 'city' discovered on underwater mountain

Tens of millions of brittle-stars, a relative of the starfish, were found carpeting the flat top of a 750m (2,500ft) seamount in the Macquarie Ridge - a 1,400km (870 mile) range of marine mountains running south from New Zealand.

The colony is mostly made up of brittle stars (Ophiuroidea), which are closely related to starfish. Researchers named the seamount habitat “brittle-star city” because of the vast numbers of the animal. Tens of millions of the creatures were found living crammed together.

They are able to survive because of a swirling circumpolar current flowing over and around the seamount. It allows the brittle stars to capture passing food simply by raising their arms, and also sweeps away would-be predators such as fish. Brittle-stars were thought to be the only animals able to keep their footing amid unusually strong currents.

The city was discovered during an expedition by the Census of Marine Life to survey the Macquarie Ridge aboard the research vessel Tangaroa.

The suspected new species await confirmation by a detailed analysis of their structures and comparison with known species.