White Blooded: The Icefish

Among known vertebrates, of which there are around 50,000, there is only one that lacks red blood cells and hemoglobin: Chaenocephalus aceratus, also known as the Icefish. Its blood runs transparent, like the icy waters it calls home.  And the interesting story of its discovery in 1927 by zoologist Ditlef Rustad was recently chronicled by Dan Cossins on The Scientist.