Image: Jennifer O'Leary, Hopkins Marine Station
Thousands of jumbo squid have beached themselves on central California shores this week, committing mass "suicide." But despite decades of study into the phenomenon in which the squid essentially fling themselves onto shore, the cause of these mass beachings have been a mystery.
But a few intriguing clues suggest poisonous algae that form so-called red tides may be intoxicating the Humboldt squid and causing the disoriented animals to swim ashore in Monterey Bay, said William Gilly, a marine biologist at Stanford University's Hopkins Marine Station in Pacific Grove, Calif.
Each of the strandings has corresponded to a red tide, in which algae bloom and release an extremely potent brain toxin, Gilly said. This fall, the red tides have occurred every three weeks, around the same time as the squid beachings, he said. (The squid have been stranding in large numbers for years, with no known cause.)
"It's not exactly a smoking gun, but it's pretty circumstantial evidence that there is some link," Gilly told LiveScience. [See Photos of the Stranded Humboldt Squid]
Decades old mystery
For decades, beach lovers have reported bizarre mass strandings where throngs of Humboldt squid (Dosidicus gigas), also called jumbo squid, fling themselves ashore, said Hannah Rosen, a marine biology doctoral candidate at the Hopkins Marine Station.
"For some reason they just start swimming for the beach," Rosen told LiveScience. "They'll asphyxiate because they're out of the water too long. People have tried to throw them back in the water, and a lot of times the squid will just head right back for the beach."
Before this, scientists in 2002 and 2006 noticed mass squid strandings from the Gulf of Mexico all the way to Alaska, Gilly said.
But the cause of the mass squid deaths was an enigma. The strandings seem to happen whenever schools of squid invade new territory, leading some to suggest the creatures simply get lost and don't realize they are out of the water until it is too late. The squid washing ashore are juvenile size, about 1 foot (0.3 meters) long, and hadn't been traveled to Monterey Bay before this fall. This season's stranding, which started Oct. 9, happened around the time Humboldt squid entered the bay.
Deadly algae
Other scientists have proposed that red tides that release a lethal toxin called domoic acid may be intoxicating the squid and disorienting them. But when researchers tested the stranded squid for domoic acid, they found only trace amounts of the chemical, Gilly said.
The poisonous chemical mimics a brain chemical called glutamate in mammals, though domoic acid is 10,000 times more potent than glutamate. The similar structure means domoic acid can bind to glutamate receptors on neurons. In turn, the receptor opens channels that let calcium into the cell. At high levels the poison causes brain cells to go haywire and fire like crazy, so much that they fill up with calcium, burst and die, Gilly said. [10 Weird Facts About the Brain]
Humans who eat shellfish contaminated with this red-tide toxin get amnesic shellfish poisoning, because the toxin destroys their brain's memory center called the hippocampus. Sea lions that eat similarly poisoned anchovies or krill go into seizures or become disoriented and behave bizarrely.
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6 Comments
Add CommentBut if it's just drunken, erratic behavior, why is it only toward the beach? Seems they would need to also see the squid swimming out to sea, or straight down, or other random behavior to attribute intoxicated disorientation.
Reply | Report Abuse | Link to thisRandoo
Reply | Report Abuse | Link to thisThe squids are heading to Taco bell like most drunks do
Suicidal squid are becoming a major problem. The root cause of their erratic behavior is not environmental as the "Henny Penny" like alarmists, so common in our scientific community, would have you believe. Squid behavior is governed by genetics. It only take one bad seed to ultimately spoil the whole squid population. We, as responsible stewards of this planet, should study the squid phenomena and apply those lessons where we have some control - the human population. Random and careless breeding practices are destroying our society and will ultimately destroy our planet.
Reply | Report Abuse | Link to thisHaving seen the effects of domoic acid on sea lions I think this is a very likely cause for the squids going aground. Escaping predators, or thinking they're escaping predators could be part of this.
Reply | Report Abuse | Link to thisThe sea lions bob back and forth between going into the water or further out of the water. When somebody approached them often went straight for the water. When I was walking my dogs I would avoid them when they're on the beach but some people think they're "helping".
littleredtop That 'selective breeding' has been tried by humans. Nazi Germany and Master Race come to mind.
Reply | Report Abuse | Link to thislittleredtop, would you care to elaborate? Which breeding practices are you referring to? I suppose you have some plan where you, or like minded people, are in charge of a more "refined" human breeding program to weed out the undesirables. Perhaps people will have to undergo genetic testing and behavioral analysis and those deemed unfit to breed would be sterilized. An absolutely sickening idea.
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