At One Undersea Volcano, Star Heaven

Brittle stars, or ophiuroid ophiacantha, are Echinoderms, as are starfish -- meaning they have a five-part body structure. But they're otherwise not related to starfish.

Melbourne-based marine biologist Tim O'Hara, a brittle star specialist, said the vast collection of brittle stars, or ophiuroid ophiacantha, is "like a relic of ancient times."

"Normally fish would prey on them and eat them ... so for whatever reason there's a lack of fish predation there and it's seen this particular animal flourish," he said.

O'Hara, who was not part of the voyage, said the speed of the sea current in the area may partly explain why fish were not feeding on the tiny animals.

The Circumpolar Current merges the waters of the Atlantic, Indian and Pacific oceans and carries up to 150 times the volume of water flowing in all the world's rivers, oceanographer Mike Williams said.

Australian oceanographer Steve Rintoul, who was not involved in the expedition, said there have been few measurements of the Antarctic Circumpolar Current, which "strongly influences regional and global climate" by carrying vast amounts of water and heat across oceans.

Fewer than 200 of the world's estimated 100,000 sea mounts that rise more than a half a mile above the sea floor have been studied in any detail.

Related Links:

Jessica Marshall's blog: EnvironMental Case

How Stuff Works: The Geography of Oceans

Planet Green