Dense brittlestar colony discovered on Macquarie Ridge seamount.

Deep sea exploration is one of the last and most exciting scientific frontiers on our planet. The 10-year long Census of Marine Life project has already made some pretty cool discoveries. Last month, scientists aboard the Research Vessel Tangaroa of New Zealand’s National Institute of Water & Atmospheric Research (NIWA) discovered an seemingly unlikely colony of starfish-like echinoderms called brittlestars living at the summit of a huge seamount in the Macquarie Ridge, a large underwater mountain range between New Zealand and Antarctica (see map at the end of this post). These critters take advantage of the dramatic 4km/hr ocean current at the summit, capturing prey as it is blown over the seamount. 4km/hr may not sound like much, but you have to consider the immense breadth of the current. According to Dr. Mike Willams of NIWA, “This current is estimated to be 110 to 150 times larger than all the water flowing in all the rivers of the world.” Wow. The ridge where the colony was discovered was about 750 m above the ocean floor, and 90 m below the ocean surface.

While fishermen often catch rare organisms from these places (and toss them overboard), relatively little scientific exploration of the world’s approximately 100,000 seamounts that are taller than 1km above the sea floor has been done (less than 200 of them have been sampled in detail, by CoML’s count). Most have been dominated by corals and sponges, which is why the brittlestars were an unexpected discovery. It’ll certainly be exciting to see what else CoML finds. Check out the press release and the image gallery from the Tangaroa expedition to the Macquarie Ridge.