Tuesday, 6 May 2014 | MYT 4:15 PM

Thousands of starfish die from mystery plague, leaving scientists dumbstruck

Scientists are struggling in a race against time to find what’s causing a disease that’s been killing thousands of starfish since last year – resulting in gruesome deaths that physically tear and melt their bodies apart.

Starfish – or more accurately sea stars – are being obliterated on both sides of the North American coast by an unexplained disease that causes white lesions to appear before the animal’s body sags and ruptures and it spills out its internal organs. In some cases, the starfish's arms rip themselves from the rest of the body. In the end, the starfish 'melts' into a slimy gooey substance.

A time-lapse video uploaded by Vancouver Aquarium in November last year of an infected starfish ripping itself apart shocked viewers by how fast it killed. In just seven hours, the starfish was in pieces.

The disease, referred to as ‘sea star wasting disease’, first appeared last year and is showing no indication of abating. So far, the mysterious killer has been decimating 18 different species along their entire range on the North American Pacific Coast.

With a mortality rate as high as 95%, entire starfish populations from as far north as Alaska to Southern California and Mexico have been wiped out. The disease has also been spotted on the East Coast but deaths there have been less staggering.

“The magnitude of it is very concerning. There’s the potential that some of these species could actually go extinct,” said Cornell University ecologist Drew Harvell, one of the scientists involved in the loosely organised search for a cause.

Laid to waste: Arms of a sunflower sea star (above) ripped apart and left for dead on the seafloor by the 'sea star wasting disease', a mysterious illness that have left scientists puzzled as to what's causing it. Below, the gooey remains of a pink sea star obliterated by the disease. 

The scientists have ruled out possible culprits including fungi, some parasites and certain other micro-organisms, and are currently taking a hard look at whether viruses or bacteria may be to blame. But their search has left them with more questions than answers.

“What is it that has caused this? Where did it come from? If it’s exotic, how did it get here? Is it something that’s likely to be repeated?” asked Pete Raimondi, chairman of the Department of Ecology and Evolutionary Biology at the University of California, Santa Cruz.

Raimondi expressed concern that the star-killer could be a harbinger of bad things to come for other marine species. “This is a really difficult disease in lots of ways because it’s very virulent,” Raimondi said.

He added that they’re wondering whether the starfish were infected by a virus, bacterium or something else unwittingly imported to the region, or whether a pathogen already present somehow became more dangerous.

Although starfish have been victims of previous diseases in past decades that reduced their numbers, the current plague is critically serious. “I wish we had a sign that it was petering out, but believe me it definitely is not,” Harvell said.

Scientists prefer to call the animals sea star rather than starfish because they are technically not fish but rather echinoderms, cousins of sand dollars, sea cucumbers and sea urchins. Most have five arms, although some some species can have more.

They are remarkably durable creatures, and when healthy are able to regenerate lost limbs. Though slow-moving, they are active predators and use suction to pull shells apart to get at the soft body inside. When the shells are pried opened, the starfish pushes its stomach out of its body and into the prey, secreting enzymes that digest the victim’s soft body parts alive.

They are significant predators in their ecosystems, the scientists said. “These animals are really important ecologically. If they do go extinct, or at least ecologically extinct for some period of time, there undoubtedly would be some really huge impacts on the ecosystems that they live in,” said Bruce Menge, a marine community ecologist at Oregon State University. 

So has anyone told Patrick yet? – Reuters

Tags / Keywords: Lifestyle , Environment , Features , Science , Nature , Wildlife , Environment , epidemic , starfish , sea star , wasting disease , plague , mystery , mysterious


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