This scaleless Antarctic fish has crystal clear blood

This is Chionodraco rastrospinosus, an ocellated deep sea ice fish that swims in the frigid waters off Antarctica. Unlike other vertebrates, its blood is completely devoid of hemoglobin — and is therefore translucent. Combine that with its scaleless features, and you have one of the more unique creatures on the planet.


This fish is a bit of a conundrum for marine biologists. Hemoglobin is crucial protein for vertebrates; it transports oxygen around the body and gives blood its vivid red color.

According to Satoshi Tada, a biologist tending to the only two specimens in captivity, the fish can live without hemoglobin on account of its oversized heart and the blood plasma that circulates through its body.


And interestingly, the skin — without any scales — may be able to absorb oxygen from the Antarctic waters, where it can be found a depths exceeding 3,300 feet (one kilometer).

As Tada told the AFP, the two C. rastrospinosus under observation have spawned, which should give the biologists further opportunities to study the fish and gain a better understanding of its unique features.

Source: France24; h/t LiveScience.

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Dr Emilio Lizardo

That is truly bizarre. Comparative Physiology was decades ago, but most terrestrial mammals have better than 95% of the oxygen in the blood bound to hemoglobin and only a small portion dissolved in the plasma. The metabolism of this fish must be nearly anearobic unless it can dissolve a huge amount of oxygen in its plasma.