Why Do These Lizards Have Toxic Lime-green Blood?

  • Why Do These Lizards Have Toxic Lime-green Blood?

Why Do These Lizards Have Toxic Lime-green Blood?

Researchers said on Wednesday that a DNA study resolved their family tree, finding that green-bloodedness evolved four different times among lizards called skinks on New Guinea.

The high blood concentration of the green bile pigment biliverdin overwhelms the intense crimson colour of red blood cells, resulting in a striking lime-green coloration of their blood, muscles, bones and mucosal tissues, said LSU biologist Christopher Austin, a curator at the museum.

"We were excited by the complex history of these animals and surprised by the breadth of green-blooded lineages across lizards", study lead researcher Zachary Rodriguez, a doctoral candidate in the Department of Biological Sciences at Louisiana State University, said in a statement. And scientists have been trying hard to figure out what benefit this characteristic - caused by high levels of an ordinarily toxic green bile pigment - may give them.

Why do some lizards have green blood? However, the function of green bile pigment in these lizards is still uncertain. But researchers discovered something odd in New Guinea's Prasinohaema lizards.

Prasinohaema prehensicauda, a green-blooded skinkCHRISTOPHER AUSTINSeveral species of New Guinea skinks, a type of lizard, are just as colorful inside as they are outside-bright green blood runs through their veins, an oddity among animals.

"Oh, these animals are gorgeous, truly some of the most attractive and enigmatic lizards in the world, living on one of the most mega-diverse islands on the planet", Austin said.

It turns out that the green-blooded lizards are not each other's closest relatives, according to a report in the journal Science Advances. In this tube, red blood cells are on the right and green blood plasma is on the left.

"Our next goal is to identify the genes responsible for green blood", Rodriguez said.

What's more, he's personally eaten raw red-blooded skinks and green-blooded skinks, and found that both tasted about the same-kind of like "bad sushi", says Austin. We only have low levels of biliverdin in our bodies, and we can spot it at the surface whenever we get hurt and develop bruises.

Lately the scientists have been wondering if the lizards' green blood might protect them from parasites like malaria - although Austin admits that this is "pretty speculative".

A blood that is so toxic, these reptiles are perfectly healthy. The fact that green blood emerged independently four times in separate lineages suggests that it must have had an adaptive value, but the team isn't quite sure what that value is yet. He notes that elevated levels of biliverdin have been found in some fish, and they may also explain the green blood in some frogs.