Image: Apherusa glacialis
R. Gradinger and B. Bluhm / UAF / NOAA
The species known as Apherusa glacialis ranks as the most abundant of the ice-loving amphipods.
By Senior writer
updated 9/11/2012 9:03:52 PM ET 2012-09-12T01:03:52

Flealike crustaceans that rely on Arctic ice may be using deep ocean currents as a sort of conveyor belt to bring them back to the pack after their ice has drifted out to sea, new research suggests.

If it is indeed how the tiny crustaceans keep from going too far out to sea, it is a clever transportation method that could become their way to survive ice-free Arctic summers as the globe heats up.

"Our findings may ultimately change the perception of ice fauna as a biota imminently threatened by the predicted disappearance of perennial sea ice," the researchers wrote Tuesday in the journal Biology Letters.

Losing ice
Arctic summers are becoming less icy as the climate changes. This summer set an all-time record for least Arctic sea-ice cover, with only 1.58 million square miles (4.10 million square kilometers) left in late August. Researchers don't know yet when summer ice will disappear entirely. Estimates range from within this decade to within perhaps 30 years. [10 Things to Know About Arctic Ice]

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Megafauna such as polar bears and walruses depend on sea ice to survive, but so do less visible animals. Amphipods, tiny crustaceans that look like a cross between shrimp and fleas, are one example. Ice-dependent amphipods spend their lives clinging to the underside of sea ice, chomping on algae that grow there.

Norwegian marine biologist Jørgen Berge of the University Centre in Svalbard and his colleagues collected the most abundant of these ice-loving amphipods, a dark-eyed, transparent species called Apherusa glacialis, in plankton nets in January. They found the shrimplike crustaceans at depths between about 650 and 6,500 feet (200 to 2,000 meters). About half of the haul was made up of egg-bearing females ― an unusual find for researchers, who don't normally take samples of these winter-breeding species in January. (Few people brave Arctic winters even in the name of science.)

Global warming adaptation?
The discovery of deep-dwelling A. glacialis prompted Berge and his colleagues to come up with a theory of how these creatures manage to stay on ice despite seasonal melting. As the sea ice moves out into the oceans, they suggest, the amphipods ride along. When they get far enough out, the crustaceans drop down to depth. Between 650 feet and about 3,000 feet (200 and 900 meters) below the ocean surface, the amphipods find themselves caught up in currents that actually move toward shore instead of away. These currents could provide a passive way for the amphipods to float back to ice-covered climes.

The researchers calculate that the distance covered during a nine- to 10-month float on a chunk of sea ice could be made up in the opposite direction by riding a deep-ocean current for two to three months. In this way, amphipods could survive ice-free summers and make it back in time for the winter ice to form, providing them with a new habitat and source of food.

These conclusions have "yet to be rigorously tested," the researchers warn. Nevertheless, they could explain how amphipods as a group survived the last period of ice-free summers about 8,000 years ago.

Much more work is needed to understand how amphipods will fare in a warming world, the researchers wrote. Nevertheless, the findings provide some hope.

"If our observations prove to be of a more general character, ice-associated fauna such as A. glacialis is less threatened by the predicted disappearance of Arctic summer sea ice than previously assumed," they wrote.

Follow Stephanie Pappas on Twitter @sipappasor LiveScience @livescience. We're also on Facebook and Google+.

© 2012 All rights reserved.

Explainer: Top 10 oddballs of the animal world

  • Image: Platypus
    Healesville Sanctuary

    From the outside, the platypus looks like a grade-school art project assembled by a kid too busy making spitballs to pay attention in class. The creature, which is classified as a mammal, has a duck's bill and webbed feet, lays eggs like a reptile, but has fur and rears its young on milk.

    Researchers say the platypus genome is equally cobbled together from bird, reptile and mammalian lineages. One more oddity: Males can deliver venom from tiny spurs on each hind limb. Click on the "Next" arrow above to learn about nine more oddballs in the animal world.

    More info: Mixed-up platypus genome unscrambled

    — By John Roach, contributor

  • Colossal squid has plate-sized eye


    In April 2008, scientists in New Zealand looked a thawing colossal squid in the eye and discovered that the eye is, well, colossal — about the size of a dinner plate. That makes it the largest animal eye on Earth. Fishermen caught the 1,000-pound creature last year in Antarctic waters and froze it intact for scientific study. Colossal squids can reach 46 feet in length and have tentacles equipped with suckers and hooks. Scientists believe the creatures can descend to 6,500 feet and are active, aggressive hunters.

    More info: Huge squid caught, could be biggest ever

  • Aye-aye gives grubs the finger

    Duke University Lemur Center

    The aye-aye is a bushy-tailed primate from Madagascar with big eyes and bat ears. But call it funny-looking and it just might extend its extra-long middle finger in your general direction. The member of the lemur family otherwise uses the extended digit to fish out grubs from the crevices of trees. Captive aye-ayes such as the one shown here from Duke University are teaching scientists about the evolution of color vision.

    Learn more about the brainiac of all lemurs

  • Star-nosed mole sniffs out food, fast

    Image: Star-nosed mole
    Kenneth C. Catania / Vanderbilt

    The fleshy appendages that ring the snout of the star-nosed mole, shown here, make it one strange-looking creature. But when it comes to eating, those 22 tentacles help the mole detect and devour food faster than the human eye can follow — in a fraction of a second. Researchers say the speedy feeding allows the mole to prey on small insect larvae that would otherwise be too energetically costly to eat. The creature lives and forages under the cover of marshes and wetlands along the east coast of North America.

  • Burrowing toad is genetically different

    Robert Puschendorf

    For an amphibian, the stocky and squat Mexican burrowing toad doesn't look all that strange, but it's actually unique. A global conservation program called EDGE of Existence ranks the toad as the most "evolutionarily distinct" amphibian in the world. A fruit bat, polar bear, killer whale, kangaroo and human are all more closely related to one another than the toad is to any other species, according to the program. The Mexican burrowing toad, as its name suggests, spends most of the year underground, coming out only after particularly heavy rains to breed in pools of water.

    Learn about other bizarre amphibians under threat

  • Yeti crab lurks on the ocean bottom

    A Fifis  /  AP

    Named after the legendary shaggy man-beast that tromps through the snows in some of the world's tallest mountains, the Yeti crab blindly scurries about hydrothermal vents along a ridge at the bottom of the Pacific Ocean. First observed in 2005, the crab, officially named Kiwa hirsute, sports a carpet of pale yellow hairs on its arms. Scientists suspect the crab uses those hairs either to farm bacteria or to feel its way around the seafloor for food and potential mates.

    More info: Scientists to list all species on Web

  • Narwhals, the 'unicorn' whales

    Glenn Williams / Harvard Medical School

    Unicorns are purely mythical creatures, but the myths may have been inspired by narwhals. Most males and some females among the 2,200- to 3,500-pound whales sport an 8-foot-long appendage that emerges from the left side of their upper jaw. Scientists recently discovered that the elongated tooth is packed with nerve endings, making it extraordinarily sensitive. The whales may use it to determine the salinity of water and search for food. Male narwhals are also known to rub their tusks together, presumably because it gives off a unique sensation.

    More info: Mystery of 'unicorn' whale solved

  • Sucker-footed bats stick to Madagascar

    Field Museum (left); Bat Conservation Int'l (right)

    In January 2007, scientists announced the discovery of a new species of bat that uses suckers on its thumbs and hind feet to stick to broad-leafed plants such as the traveler's palm. The new species, Myzopoda schliemanni (left image), was found on the dry, western side of the African island nation of Madagascar and is closely related to another sucker-footed bat called Myzopoda aurita (right image) that lives in the humid eastern forests. Conservationists were heartened by the discovery because it suggests the bats can adapt to pioneering broad-leafed plants in deforested areas. Only about 8 percent of the island's original forest cover remains.

    Watch NBC video: What's killing all the bats?

  • Long-eared jerboa hops onto the screen

    Image: Long-eared jerboa

    In December 2007, conservationists released the first known footage of an endangered rodent they've nicknamed the "Mickey Mouse of the Desert." Known more formally as the long-eared jerboa, the little critter has ears about one-third larger than its head, and legs that allow for hopping like a kangaroo. The International Union for Conservation of Nature lists the species as endangered. One threat: the domestic cat.

    More info: Mongolian 'Mickey Mouse' caught on tape

  • Ligers, wholphins and grolar bears, oh my!

    Image: Liger
    TODAY show

    Every now and again, trysts between two different species result in oddball offspring that capture the public's fascination. Ligers, which are a cross between a male lion and a female tiger, were immortalized in the 2004 cult movie "Napoleon Dynamite": The main character of the 2004 cult movie, played by Jon Heder, describes it as "pretty much my favorite animal." (A real one is shown above.) Other popular hybrids include wholphins, which are a cross between false killer whales and Atlantic bottlenose dolphins; and the "grolar bear," a cross between a grizzly bear and polar bear.

    Watch NBC video of a liger
    Whale-dolphin hybrid has baby wholphin
    Hairy hybrid: Half grizzly, half polar bear


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