Explorers marvel at 'Brittlestar City' on seamount in powerful current swirling around ...(regation of another filter feeder the br...)

They photographed brown-black brittlestars numbering hundreds per square meter and estimate tens of millions of them populate the 100 square km flat top of the seamount.

Brittlestars are echinoderms, relatives to starfish, sea cucumbers, sea lilies, and sea urchins. The two brittlestar species observed were tentatively identified via photographs sent from the ship to the Museum Victoria in Melbourne, Australia.

There, taxonomist Tim OHara determined that the smaller, densely packed brown-black brittlestar species, found living arm tip to arm tip on the sand and cobble substrate of the peak, were likely Ophiacantha otagoensis or Ophiacantha fidelis.

Larger orange-red species discovered down the seamounts flanks, filmed waving arms in the current to collect passing food, were likely Ophiacantha rosea.

We were excited to see such a huge assemblage of brittlestars on the Macquarie Ridge seamount. Not only is it amazing to see a vast array of one type of organism but the implications of the find for our understanding of the relative uniqueness of seamount assemblages are potentially far-reaching. said ecologist Dr. Ashley Rowden of NIWA.

The ship towed special sleds to collect seamount organisms. Thousands of specimens of all kinds were gathered from eight seamounts in over 30 sled collections and now fill almost 1,600 vials, jars and bags, to be sent from NIWA to taxonomists in New Zealand, Australia and overseas.

Full identifications may take many years. The eight biologists on board believe some species collected have never before been recorded in the region while some may be new to science.

A Deep Towed Imaging Syst
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