Green blood in lizards probably evolved four times | Science News

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Green blood in lizards probably evolved four times

Studying the bizarre color might someday offer insights into human jaundice

By
2:10pm, May 16, 2018
green blooded lizard

BLEEDS GREEN The few lizards with green blood, such as this green skink from Papua New Guinea, may have acquired the coloring via a spotty pattern of evolutionary history. Their muscles, bones, tongues and gums also look greenish.

Green blood is weird enough. But now the first genealogical tree tracing green blood in New Guinea’s Prasinohaema lizards is suggesting something even odder.

These skinks have been lumped into one genus just because of blood color, says biologist Christopher Austin of Louisiana State University in Baton Rouge. Yet they don’t all turn out to be close relatives. Green blood looks as if it arose four separate times in the island’s lizards, he and colleagues propose May 16 in Science Advances.

These lizards do have crimson red blood cells, but that color is overwhelmed by extreme buildups of a green pigment called biliverdin at levels that could kill other animals. Biliverdin forms as the oxygen-carrying hemoglobin molecules break down in dead red blood cells. In humans, biliverdin is converted into the bile that, in excess, causes yellow jaundice. An excess of the

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