Warm waters and infectious disease have been identified as the cause of the death of a starfish on the Pacific coast, says the newly published study.
The Sunflower Sea Stars are among the world's largest starfish and come in a variety of bright colors, including purple and orange. Some of them grow more than one meter and are so fast "literally cross the coast," says Joseph Haidos, senior author of the study.
"But when this disease happens, it's like a zombie apocalypse," said Gaydos, who is with the University of California Sea of California, Davis.
"It can have 24 weapons and suddenly move around and hands are just falling. And suddenly it seems that the whole body melts."
So, what was once a "great, beautiful starfish", and weigh about five kilograms resembles a bunch of calcified parts in a few days, he said.
"It's really an ugly and fast-paced disease for these sunflower starfish stars."
In 2013, scientists began to notice that species species dropped between 80 and 100 percent in deep and shallow waters from Alaska and British Columbia to California. Information about the population was collected from divers and deep tracks.
Sunflower sea stars are found in the waters from hundreds of meters to only three meters.
Diego Montesino-Latorre, a study co-author, and also from the University of California, Davis, said the scientists found a connection between rising water temperatures and seeing lesser sea stars.
Geodos said the rise in water temperature is not the same in all areas.
The oceans are not "as tubs" with consistent temperatures, he said, adding that some places in California have seen an increase of about 4 degrees, while places in Washington have seen an increase of 2.5 degrees Celsius.
One theory suggested by scientists is that temperature rises makes marine stars more susceptible to the disease that has already been present, especially since marine stars do not have complex immune systems, he said.
Co-author of the study, Drury Harwell, a professor of ecology and evolutionary biology at Cornell University, said the heat wave in oceans caused by global warming made the sea star losing the disease worse and more quickly killing a starfish.
Geodos said that sunflower sea stars are unpainted predators, and when they reduce the number of sea urchins it can increase.
Such disease outbreaks can have a major consequence of the entire ecosystem, he said.
"Urchins can destroy algae forests, and then, when you lose algae, you will lose biodiversity," he said. "Kelp is a place for fish to hide, algae is food for other animals."
Kelp beds were already plagued, he added.
"Kelp also does not do well when the ocean temperatures are rising, so it's like a double blow for algae."
One of the options for algae assistance is the selective harvest of sea urchins, which is being tested in California, Geidos said.
And the option to help the sunflower star population is raising prisoners, where animals that are more resistant to the virus can be selected, he said.
Gaydos said that death is a wake-up call.
"It's hard to keep an eye on what's happening in the ocean, but we need to pay attention, because it happened for a very short period of time," he said. "To have a complete look almost disappearing, it's not good."