Marine Scientists Discover Rare Enteropneust Acorn Worms in Atlantic Ocean

Posted on July 7, 2010

Scientists discovered different varities of the Enteropneust acorn worm during a search of deep-sea life in the Atlantic Ocean. The researchers believe the acorn worm may be a transitional species between invertebrates and backboned animals. The scientists were completing the last leg of MAR-ECO, an international research program, which is part of the Census of Marine Life. The research was conducted using Isis, the UK's deepest diving remotely operated vehicle (ROV) to depths of between 700m right down to 3,600m. Researchers surveyed flat plains, cliff faces and slopes of the giant mountain range that divides the Atlantic Ocean into two halves, east and west.

The researchers say little is known about these deep-sea enteropneust acorn worms. The worms leave spiral traces on the sea floor. They have no eyes or brain. Pink, purple and white acorn worms were discovered. Using the remotely operated Isis vehicle, high quality complete specimens of all three different-coloured species were captured and will be sent to specialists for further investigations.

Professor Monty Priede, Director of the University of Aberdeen's Oceanlab, said: "We were surprised at how different the animals were on either side of the ridge which is just tens of miles apart. In the west the cliffs faced east and in the east the cliffs faced west. The terrain looked the same, mirror images of each other, but that is where the similarity ended. It seemed like we were in a scene from Alice Through the Looking Glass. In the north-east, sea urchins were dominant on the flat plains and the cliffs were colourful and rich with sponges, corals and other life. In the north-west, the cliffs were dull grey bare rock with much less life. The north-west plains were the home of deep-sea enteropneust acorn worms. Only a few specimens, from the Pacific Ocean, were previously known to science. These worms are members of a little-known group of animals close to the missing link in evolution between backboned and invertebrate animals. The creatures were observed feeding and leaving characteristic spiral traces on the sea floor. They have no eyes, no obvious sense organs or brain but there is a head end, tail end and the primitive body plan of back-boned animals is established. One was observed showing rudimentary swimming behaviour. By the end of the expedition three different species were discovered each with a different colour, pink, purple and white with distinctly different shapes."

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