Star Fish aren’t really fish but belong to a large family of marine invertebrates, so to differentiate their symmetrical, five (or more) arms and to distance them from ‘Brittle Stars’, the term Sea Star is used. Of the 1800 or so known species of Sea Star, approximately 1500 species capture prey for food and they love mussels, oysters and other molluscs and marine life on the sea floor.
Humans love them for their shapes and colours and we remain fascinated by their still-mysterious biology. Sea Stars can project their stomach outside of their body, around large molluscs for external digestion or they can swallow smaller ones whole. All of that food energy helps a female (usually) produce up to 2.5 million eggs, often into the surrounding current, while the males release sperm for external fertilization. But that is not the only waySea Stars can multiply in number.
If the severed arm of a Sea Star contains a portion of the nerve ring within the central body, a new Sea Star can grow from that severed arm. Before this was known, oyster and mussel farmers would remove the predatory Sea Stars from their oyster beds, cut them up and throw them back into the ocean.
Now they are quite suddenly and very mysteriously disappearing from the coastal waters of North America, most noticeably the West coast but some reduction in numbers of similar species are being recorded on the East coast as well. In Western Canada, researchers noticed an impossibly sharp decline in numbers of shallow water Sea Stars (the most prevalent) normally inhabiting the coastal waters of British Columbia and alarms were sounded in the scientific community. U.S. marine biologists reported the trend in June of 2013, noting that 90% to 95% of the hundreds of Sea Stars studied in California had died.
Not only is it the speed with which the Sea Stars are dying a mystery, so too is the way in which they perish. A National Geographic article about the die-offs includes this quote from Dr. Christopher Mah of the Smithsonian Institute, to illustrate the strange findings:
“[The starfish] seem to waste away, ‘deflate’ a little, and then just … disintegrate. The arms just detach, and the central disc falls apart. It seems to happen rapidly, and not just dead animals undergoing decomposition, as I observed single arms clinging to the rock faces, tube feet still moving, with the skin split, gills flapping in the current. I’ve seen single animals in the past looking like this, and the first dive this morning I thought it might be crabbers chopping them up and tossing them off the rocks. Then we did our second dive in an area closed to fishing, and in absolutely amazing numbers. The bottom from about 20 to 50 feet [6 to 15 meters] was absolutely littered with arms, oral discs, tube feet, gonads and gills … it was kind of creepy.”
Although high rates of mortality are seen among the most common species, Sunflower Sea Star (P. helianthoides), now other species of Star Fish are found dead in the same areas. What scientists are asking themselves now is if this ‘epidemic’ as the Vancouver Aquarium called it in late September is restricted to the northern Pacific or will it become endemic in all know populations.
Pacific coast fish contain very high levels of radiation: http://enenews.com/canada-tv-new-concerns-about-radiation-levels-in-fish-from-pacific-these-numbers-are-just-staggering-contamination-up-considerably-its-a-major-event-worldwide-video
Plots of Fukushima radiation across the Pacific by several countries: http://www.globalresearch.ca/fukushima-radiation-levels-will-concentrate-in-pockets-at-specific-us-and-canada-west-coast-locations/5356528