Millions of sea stars have vanished from the West Coast over the past year, affecting habitats ranging from Alaska all the way to Mexico, with some deaths even detected off the East Coast.
Perhaps one of the most peculiar facts about the event is that both wild and captive sea stars are succumbing to what researchers refer to as "wasting syndrome," a condition that causes the sea stars' limbs to contort unnaturally, form lesions and eventually tear off, leaving the animal fatally deflated.
Dozens of marine biologists from reputable aquariums and other institutions across the United States and parts of Mexico are scrambling for answers, unable to do anything but theorize about what could be causing the massive die-offs.
"We're trying really hard but it's a really complicated puzzle to put together because there's no real foundation (of knowledge about) the sea stars, so it's hard to tell what's normal," said Lesanna Lahner, a staff engineer at the Seattle Aquarium.
Scientists are completely stumped over the massive die-off of star fish
Some experts have blamed radiation from Fukushima, whose effects were predicted to hit the West Coast this year, while others suggest that warming sea waters could be contributing to the sea star's susceptibility to a mysterious pathogen.
Another interesting, and quite puzzling, fact is that the sunflower and ochre sea stars seem to be plagued with the disease more severely than rubbery-bodied starfish, according to a report by the The Bellingham Herald.
Both leather and blood starfish have a rubbery outer coating that's seemingly acting as a protectant against the disease. While these types of starfish aren't completely resilient, they're apparently more resistant than the fleshy-bodied sea stars.
Unlike other starfish, the leather sea star doesn't have spines. They have small, feathery sacks used for respiration in each arm. They also don't have blood, but instead use seawater to pump nutrients around their bodies.
More than 50 percent of captive sea stars die at Washington aquarium
Washington's Point Defiance Zoo & Aquarium has lost more than half of their 369 sea stars to wasting syndrome, including all of their sunflower starfish.
"We have to suspect that it's causing pain even though we don't know (for certain)," said Lahner.
Biologists are monitoring the animals that begin to show arthritis-like symptoms, an indication of the syndrome, quarantining them in a back room where the water is more filtered.
Starfish are what's known as "keystone" species in the ocean, built so sensitively into their ecosystems that their demise could wreak havoc for other marine animals.
"(Sea stars) are such a key player in keeping our ecosystem healthy," added Lahner. "We depend upon a healthy ecosystem for a variety of things like commercial fishing and recreational activities."
Experts say mussels, one of the sea star's most desired foods, are growing exponentially, which could result in the mussels overtaking "less hardy species."
This isn't the first time wasting syndrome has been observed. Throughout the 1970s, 1980s and 1990s, researchers saw a similar phenomenon, but the die-offs weren't occurring anywhere near the scale at which they are today.
The disease struck so quickly in the past that, by the time the outbreaks were noticed, they were over, said Lahner.
Some aquariums are using antibiotics to treat starfish suffering from wasting syndrome; however, the move has attracted controversy.
"It's a broad spectrum antibiotic so it's either killing the primary infection or a secondary infection as a result of the disease," Lahner said. "Some are worried that treating the sea stars could create a resistant superbug."
Antibiotics have seemingly slowed the disease but aren't curing it.
"Initially you don't know what's going on," said Neil Allen, curator of aquatics at the Tacoma aquarium.
"You don't know which ones are sick and which ones aren't. Their arms get contorted. It looks like they have arthritis and once we see that, we know they're affected."
Written by Julie Wilson
Featured image: Point Walpole Sea Star by Mack Lundy (CC - Flickr)