By Marlene Cimons, National Science Foundation
Jumbo squid of the species Dosidicus gigas have a high demand for oxygen. Yet they can go for hours with very little of it, and still swim fast enough to hunt for food—or avoid becoming food themselves. This unusual ability could explain why they like to hang out in these toxic environments.
“It’s a great place to feed because everything else there is not moving very well, and it’s a great place to hide from predators,’’ said Kelly Benoit-Bird, associate professor of biological oceanography in the College of Oceanic and Atmospheric Sciences at Oregon State University. “These squid, even in low oxygen, can still move extremely fast. We’re trying to figure out why and how.’’
Benoit-Bird, who was among those named last week to receive a prestigious $500,000 MacArthur “genius’’ award, a “no-strings attached’’ fellowship, is collaborating with marine biologist William Gilly, of Stanford University’s Hopkins Marine Station, and Brad Seibel, a comparative animal physiologist at the University of Rhode Island, to study the behavior of this unusual creature, also known as the Humboldt squid.
‘These squid can operate for many hours at 10 percent oxygen or less, and snap right out of it,’’ Gilly said. “That would certainly be a talent humans could use.’’
The National Science Foundation is supporting the work with $463,873 in funding as part of the American Recovery and Reinvestment Act of 2009, enabling the research team to, among other things, support a number of graduate students “who wouldn’t otherwise be getting trained and paid,’’ Benoit-Bird said.
The research, which uses sophisticated acoustic technology to track the squid, could provide new information about how ocean ecosystems work, including the possible effects of climate change on the movement of the squid. The Humboldt squid appears to be expanding its territory, moving from the Pacific Ocean off Mexico and California into the colder waters of the north, and spending more time in low oxygen zones, which “are thought to be expanding with climate change,’’ Seibel said.
If the scientists can gain more information about how these squid cope in a low oxygen environment, “this will help us understand why their range is expanding, and help us predict what the consequences of this expansion might be,’’ Benoit-Bird said. “We think it might have a significant impact on fisheries and ecosystem function.’’
The scientists don’t know whether the information ultimately will provide insights applicable to humans, although Gilly hopes that it will. His role is to assess the impacts of hypoxia--oxygen deprivation--on the squids’ athletic performance, including their strong swimming ability and its escape response.
“We’re doing that with experiments on live squid under controlled lab conditions, as well as using electronic tags, squid-born cameras and Kelly’s sonar to monitor what they are doing at hypoxic depths in the ocean,’’ Gilly said. “But what they do in the ocean may not reveal what they are capable of doing under hypoxic conditions, and this is especially relevant to predation on jumbo squid by sperm whales and other marine mammals.
“My background is in neurobiology and electrophysiology, so of course I think that the mechanisms involved in hypoxia tolerance of squid could have relevance to humans, and I would like to take the squid-in-lab experiments exactly in that direction,’’ he added. “Once we see how the squid is impaired, we can use electrophysiological methods to get at exactly what elements in the neural pathways are impaired, and then use finer techniques to hone in and get at cellular and molecular mechanisms.’’
Seibel said that the response of squid to low oxygen appears to be fairly common among marine organisms. What makes them unique, however, is their high oxygen demand. “Most species with equivalent metabolic demands—tuna, for example—are unable to tolerate low oxygen,’’ he said.
“They are adapted by having blood that is capable of extracting oxygen from hypoxic waters,” he added. “When oxygen drops too low, these squids are able to suppress metabolism, that is, shut down expensive cellular processes. There are analogues in mammalian cell research, but I doubt we’ll learn anything with squids that will be applicable to medicine. The questions we are answering are more related to broad oceanographic processes, like carbon flux and climate change.”
Humboldt squid live at depths of 660 to 2,300 feet in the eastern Pacific, ranging from Tierra del Fuego, an archipelago off the southernmost tip of the South American mainland, north to California. Recently, the squid have been appearing further north, as far as Sitka, Alaska, raising alarm about ecological problems possibly underlying the northward migration.
“You typically don’t expect to see them in U.S. waters,’’ Benoit-Bird said. “Usually they are in areas south. For the last decade or so, however, you can see them in the summer along the entire west coast of the United States, all the way up to the Gulf of Alaska.”
Jumbo squid can grow to human size, about six feet, and weigh as much as 100 pounds. They grow quickly, with a typical lifespan no longer than two years.
“One of the reasons these squid are ecologically interesting is that they attain their size in a year or two. They are an incredibly fast-growing species, which means they eat a lot,’’ Benoit-Bird said. “We are learning that they are very flexible predators; they can eat anything from tiny krill to things as big as they are.’’
Mexican fishermen call them diablos rojos, or “red devils,’’ because they are extremely aggressive. “I don’t think I would choose to get in the water with them when they are actively feeding,’’ Benoit-Bird said, noting, however, that they lose their propulsion when captured. Even so, “you don’t want to stick your fingers in their mouths,’’ she added.
The researchers located the squid with sophisticated sonar technology, Benoit-Bird’s field of expertise. “We emit a short pulse of sound and wait for it to travel,’’ she explained. “It hits the school and bounces back, and that’s how we can determine where they are. We use multiple frequencies at the same time, different pitches of sound, all above our hearing range. The squid have a unique frequency signature, so we can distinguish them from other fish.’’
Many scientists previously believed that sonar signals would not reflect off of squid. Apparently, they were wrong. “We’re not exactly sure why they reflect sound so well, but they do,’’ Benoit-Bird said. “We can distinguish individual squid, not just schools. It really gives us the possibilities of studying squid in ways we’ve never done before.’’
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