The Lizard with Green Blood

(Just Like Spock!)

Mr. Spock, the green-blooded Vulcan on Star Trek, would've said himself this is fascinating. Louisiana State University biologist and NatGeo explorer Christopher Austin studies a species of lizard, the Prasinohaema skink, that has green blood.
Actually, the skink, found almost exclusively on Papua New Guinea, not only has green blood - it has green bones and tissues as well. It's even got a green tongue, Austin remarked in this news article over at National Geographics. But why? It turns out that the animal has an unusually high concentration of the bile pigment biliverdin.
Biliverdin is a pigment that results from the breakdown of hemoglobin, which gives blood its red color. In humans, they're the reason that some bruises are green in color. Too much biliverdin is toxic and gives humans the disease called jaundice, so it's a mystery how the reptile could survive.

Austin speculated that the high level of biliverdin in the skin could actually be beneficial:

“It’s surprising because at these concentrations of bile pigments in the blood, [the skinks] should be completely jaundiced, if not dead,” Austin said.
Austin hypothesizes that the lizard evolved to tolerate the biliverdin because it may provide protection against a group of parasites called Plasmodium.
Best known for causing malaria in humans, Plasmodium also causes malaria in reptiles and birds. Austin believes that the presence of toxic biliverdin instead of hemoglobin may make it harder for Plasmodium to infect the skinks.

Carrie Arnold of National Geographic has the rest of the story.