© C. AUSTINBLEEDS 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 biliverdin itself can cause green jaundice. In one case study, levels reaching nearly 50 micromoles of biliverdin per liter of blood were deadly in humans. Yet Austin has found
lizards thriving with 714 to 1,020 micromoles per liter (
SN: 8/20/16, p. 4).
Comment: Just to show the rarity of this kind of attack on people another report from The Seattle Times contains the following pertinent extract: Interestingly, Wikipedia lists only 20 fatalities due to cougar attacks in North America between 1890 and 2011. Prior to 1990 most involved children while for the 3 most recent decades fatalities totaled 9 but with only one youngster killed
Are they becoming less wary and aggressive toward adults humans?.
See also these other reports from the last 5 years of non-fatal attacks on people: Jogger uses rock to battle cougar in attack on Vancouver Island, Canada
Cougar attacks pipeline worker near Grande Prairie, Canada
A third cougar attack within a month leaves six-year-old California boy injured
Teenager attacked by cougar in Waterton Lakes National Park, Alberta
Some wild animals are losing fear of humans: Biologist recovering after cougar assault in Grand Prairie, Alberta
Cougar attack in British Columbia leaves woman in critical condition
Man fights off cougar with skateboard; Parks Canada tracking animal
Hiker attack by mountain lion reported near Waynesboro, Virginia
Man sustains minor injuries after attack by mountain lion near Libby, Montana
Mountain lion sought after apparent attack on homeless man, Perris, California
Mother pulls mountain lion off her 5-year-old son near Aspen, Colorado