Aquarium fish has clear blood

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Tokyo Sea Life Park has put a pair of Ocellated icefish on display. This species is highly unusual in the animal kingdom as it has clear blood, rather than red.

The Ocellated icefish (Chionodraco rastrospinosus) comes from the Antarctic. The two at Tokyo Sea Life Park, which are similar to the one shown above, were found and brought back to Japan by krill fishermen and are believed to be the only specimens in a public aquarium.

Studies show that this fish's transparent blood lacks haemoglobin, a protein which carries oxygen around the body and is also responsible for its red colour. How it manages to survive without haemoglobin is unclear, although researchers think its large heart combined with blood plasma help to circulate oxygen around the body. It may also be able to absorb oxygen from the water through its skin, as it lacks scales.

The pair of fish at Tokyo Sea Life Park spawned earlier this year and scientists hope the icefish and their offspring can help researchers unlock the secrets.

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