The fish with clear blood, white gills and built-in antifreeze
This fish has completely clear blood and no red blood cells, and by all rights it should be dead.
Which one is REALLY true about the Antarctic Icefish?
The short version
The Antarctic icefish is the only known vertebrate with no haemoglobin and no red blood cells. Its blood is nearly colourless and its gills are white. It survives on oxygen dissolved in plasma using an oversized heart, wide vessels and scaleless skin, plus antifreeze proteins that stop ice crystals growing inside it.
Why it's so weird
- ✓The Antarctic Icefish is the only known vertebrate on Earth with no red blood cells at all.
- ✓The Antarctic Icefish has blood that runs pale and almost colorless, and gills that are ghostly white instead of red.
- ✓The Antarctic Icefish carries its oxygen dissolved in plain blood plasma, which works because freezing water holds so much of it.
- ✓The Antarctic Icefish pumps that thin blood with an oversized heart through extra-wide vessels, and has no scales, so oxygen soaks straight in through its skin.
- ✓The Antarctic Icefish makes antifreeze proteins that latch onto tiny ice crystals and stop them growing inside its body.
You could line up about 2 of them along a 7-year-old!
The full story
This fish has clear blood and no hemoglobin, and by all rights it should not be alive. Meet the Antarctic icefish, the only known vertebrate on Earth with no red blood cells at all. Its blood runs pale and almost colorless, and its gills are ghostly white instead of red. In water sitting below freezing, oxygen dissolves so easily that the fish can carry enough of it in plain blood plasma. To cope, it evolved an oversized heart, extra wide blood vessels, and a body with no scales, so oxygen soaks in straight through the skin. It also makes antifreeze proteins that latch onto ice crystals and stop them growing. Without those, it would freeze solid in the water it calls home. Follow for more weird animal facts.
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Antarctic Icefish gallery
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“The Antarctic Icefish is the only known vertebrate on Earth with no red blood cells at all.”
“The Antarctic Icefish is a small mouse-like marsupial from the forests of Australia, and is not a rodent at all.”
“The Antarctic Icefish has blood that runs pale and almost colorless, and gills that are ghostly white instead of red.”