A Mystery in the Ocean: Disappearing Sea Stars

Sea stars along the Pacific coast have been dying by the thousands, and researchers don't know why. The epidemic started in the summer of 2013, and has been named "sea star wasting disease." It begins with the sea stars' limbs rotting and falling off, and follows with them completely wasting away.

by Laszlo Ilyes via Flickr.com
used under Creative Commons License

A Little Bit About Sea Stars

Marine biologists are slowly replacing the name "starfish" with "sea star," due to the fact that sea stars are echinoderms, not fish. One of their most defining characteristics is their ability to regenerate limbs. They can even regenerate their entire body in some cases, because they store their vital organs in their limbs. They use the suction cups on the bottom of their body to pull apart their prey and pull it into its body to digest it. These suction cups are also what they use to move across the sea floor.

Sea stars are natural predators; not many things eat them, but they prey on anything from mussels to snails. They play an extremely important role in their marine ecosystem by maintaining the natural balance of organisms.

The Epidemic

Although sea stars are not currently considered endangered, this rapid decrease in their population poses significant long-term risks to the species, and their environment. The ailment spreads so fast and works so quickly that it is nearly impossible for scientists to research the problem before it gets worse. It has been known to wipe out an entire local group within 24 hours.

The infection tends to start with the sea stars twisting their limbs in unnatural ways, after which they develop lesions on their tentacles, which fall off soon after. Eventually, the sea star will more or less disintegrate. Historically, similar events have occurred due to environmental factors such as El Nino, but in this particular case, no environmental factors seem to be at play. 

by Andrew Reding via Flickr.com
used under Creative Commons License

This event is occurring down the entire West Coast, from Alaska to Southern California. Because of this, scientists are scrambling to find answers. No one has been able to pinpoint a specific cause yet, but the overwhelming opinion is that it is due to pathogens in the water. The question is, what is making the stars susceptible to these pathogens? Sea stars filter so much salt water through their bodies every day, finding out which pathogen might be causing this epidemic is nearly impossible. They may have various types of bacteria from sea water in their bodies at any given time, but that does not necessarily mean that any of those bacteria are causing the illness.

Researchers have been awarded a National Sciences Foundation Rapid Response Grant to continue their research and find a solution as soon as possible.

SOURCES

Steinmetz, K. (n.d.). Falling stars: Starfish dying from “disintegrating” disease. Retrieved from http://science.time.com/2013/11/05/falling-stars-starfish-dying-from-disintegrating-disease/

Weise, E. (n.d.). The starfish are dying, and no one knows why. Retrieved from http://www.usatoday.com/story/news/nation/2013/12/28/starfish-dying-wasting-disease-mystery/4208859/

Khondakar, R. (n.d.). Professor studies disappearing sea stars. Retrieved from http://cornellsun.com/blog/2014/03/26/prof-studies-disappearing-sea-stars/

Starfish (sea star). (n.d.). Retrieved from http://animals.nationalgeographic.com/animals/invertebrates/starfish/

Sea star (asterias forbesii). (n.d.). Retrieved from http://www.edc.uri.edu/restoration/html/gallery/invert/sea.htm

Ryan, J. (n.d.). Mass starfish die-off hits vancouver, may happen in washington. Retrieved from http://nwpr.org/post/mass-starfish-die-hits-vancouver-may-happen-washington