Antarctic ice fish redefines “cold-blooded”

February 16, 2009

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******If you thought that “cold-blooded” meant creatures like snakes, toads and crocodiles (or people you dislike), think again.******This Antarctic ice fish, formally called Chionodraco hamatus ”can withstand temperatures that freeze the blood of all other types of fish”, according to a report by the Census of Marine Life.******A special anti-freeze helps keep it alive in chill waters around the frozen continent. (This finger-length juvenile was photographed by Russ Hopcroft of the University of Alaska Fairbanks.)******The fish is among thousands of creatures found to be teeming in Antarctic and Arctic waters by the Census — an international project to map life in the oceans.******Scientists have counted 7,500 species of animals in the Antarctic and 5,500 in the Arctic — and at least 235 of them live at both ends of the earth. For a story, click here.******Scientists are trying to work out how the cold-loving creatures manage to live in both places, separated by a barrier of thousands of miles of warm waters. Polar bears, after all, only live in the Arctic while penguins are confined to the south.******Among theories are that chilly deep ocean currents carry larvae north from Antarctica. Scientists say that’s more likely than that got carried by a long-distance migrating bird or whale, or even by a ship (… few ships make such trips and only in recent years).******What do you think?

7 comments

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There are two possibilities. The first is that the fish were transported there somehow. And that would have to be in sufficient numbers to populate and grow successfully. These would seem difficult given these fish’s need for very cold water.Or that the two locations having similar environments separately evolved identical versions of the fish. It would be interesting to examine the DNA of these aquatic oddities.

Posted by Taver Brin | Report as abusive

wow that is amazing that there are fish that can survive in such extreme cold habitats

Is it not far more likely that these fish were populating every region of the globe during an ice age and just became separated as the ice age receded and didn’t evolve since then as they are entirely efficient in surviving in their environment. (In the same was as crocodiles haven’t evolved for hundreds of thousands of years)I’m no expert obviously.

Posted by Bryan Sheehan | Report as abusive

What is the WARMEST temp they can survive? If they can withstand, say 40 degrees(f), then it becomes easier to see how they can live in both places.

Posted by Darrell | Report as abusive

As scientist working in the Arctic Ocean Diversity Project of the Census of Marine Life, I am still amazed about the diversity of life in these frigid waters. Thanks for the comments regarding our Census work. Actually in the list of 235 common species, there is no fish species. The ice fish mentioned in the article are all endemic to Antarctica and have a unique physiology, allowing them to live at water temperatures close to minus 2 deg C. In order to minimize the freezing risk in their blood, they have these antifreeze substances and also a very low number of particles like blood cells in their body (this causes the transparent body). Some Arctic fish like Arctic cod use also antifreeze proteins.When it comes to species living at both poles, think of these regions being connected by slow cold water currents across the entire globe (we call this the conveyor belt circulation). This transfer is slow, but still fast enough to likely have contributed to the spreading of single species from pole to pole.

Posted by Rolf Gradinger | Report as abusive

Very helpful to my essay for school. Thanks.

Posted by Katya Nosarev | Report as abusive

[...] The video (which is here) looks a bit like computer rendering to me, but I know that there are transparent fish (boring link here) and mentions of this fish predate the recent news, so odds are that it’s [...]

[...] and Antarctic ice fish can survive in temperatures that are below the freezing point of pure water, which would freeze the [...]

is this the only cold blooded fish in the antarctic

Posted by nommers | Report as abusive