THE PACIFIC, Seastar/Starfish

SEASTAR-What makes a seastar/starfish go? It is "water vascular or ambulacral system"... a series of interconnected channels, tubes, valves and pumps that coordinate to move the animal, some with such strength that they can pries shellfish apart....The northern Pacific seastars usually have huge appetites and prefer shellfish, particularly oysters and mussels. In 1954, they ate 400 million yen worth of marketable shellfish in Tokyo Bay. Because of their preference for commercial shellfish, the arrival of northern Pacific seastars in Australia caused great concern. In Tasmania, these fears were largely unrealised because the seastars were not found near shellfish leases. But early in 1998, hundreds of young seastars were discovered on commercial mussel ropes in Port Phillip Bay, Victoria. These seastars could have devastated the mussel crop. According to genetic tests, the northern Pacific seastars found in Victoria probably came from Tasmania. Not surprising, considering that in 1995, the numbers of seastar young in the Derwent estuary were the highest found anywhere in the world (up to 1100 per cubic metre of water).