About 30 million years ago, the Antarctic Ocean’s temperature dropped. Few fish could survive seawater that was just above its freezing point, and they either migrated to warmer waters or went extinct.
One bottom-dweller held on. Today, the Antarctic blackfin icefish, or Chaenocephalus aceratus, thrives with no scales, blood as clear as water, and bones so thin you can see its brain through its skull.
In a paper in Nature Ecology and Evolution, scientists revealed how the icefish adapted to extreme conditions — research that provides a new way to look at human diseases such as anemia and osteoporosis. “A trait that’s maladaptive in one environment can be adaptive in another,” said H. William Detrich, a marine scientist. “We can learn a lot about human physiology and medicine by studying these evolutionary outliers.”
Frigid water holds more gasses, including oxygen, than warmer water does. But in water so cold, red blood becomes gunky, hard to pump and more likely to freeze. So the fish basically “evolved a therapy for anemia,” said John Postlethwait, a developmental biologist. It developed supersize gills and lost its scales, which enabled it to absorb the water’s oxygen through its skin. It also expanded its circulatory system with extra vasculature and a heart four times the size of closely related, red-blooded species.
Outsized bee feared extinct is spotted
It has been 38 years since scientists last spotted the insect known as Wallace’s Giant Bee, a species found only in a group of Indonesian islands called the North Malukus. With a wingspan of 2.5 inches and a body the size of a human thumb, it’s considered the world’s largest bee, and was feared extinct.
In January, a team of conservationists found a Megachile pluto, as the species is called, in the wild. The team captured the first photos and videos of a live specimen, renewing hope for survival of the species, which is threatened by deforestation.