Researchers said on Thursday they have ruled out some
possible culprits including fungi, some parasites and certain
other microorganisms and are taking a hard look at whether
viruses or bacteria may be to blame.
The starfish, also called sea stars, are being obliterated by an
unexplained wasting disease that causes white lesions to appear
before the animal's body sags and ruptures and it spills out its
"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 organized search for a cause.
Harvell said she is concerned because the mysterious pathogen is
affecting 18 different West Coast species along their entire
range. Pathogens that affect an animal's range in such a way
like a fungus that has targeted frogs can be particularly
damaging, she said.
The disease appeared last year and is showing no indication of
abating. "I wish we had a sign that it was petering out, but
believe me it definitely is not," Harvell said.
The scientists seem to have 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 disease that is killing the
starfish 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.
The researchers noted that starfish were the victims of previous
diseases in past decades that reduced their numbers, but the
current one is more serious.
The scientists are wondering whether the starfish have been
infected by a virus, bacterium or something else unwittingly
imported to the region or whether a pathogen already present
somehow became more dangerous, Raimondi added.
Scientists prefer to call the animal a sea star rather than a
starfish because these marine creatures are not fish but rather
echinoderms, cousins of sand dollars, sea cucumbers and sea
urchins. Most have five arms, although some have many more.
They are remarkably durable creatures, and when healthy are able
to regenerate lost limbs. They are 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.
They are significant predators in their ecosystems, the
"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.
(Reporting by Will Dunham; editing by Andrew Hay)
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