When Ocean Temperatures Dropped 30 Million Years Ago, Some Species Migrated to Warmer Waters; Others Developed New Traits

(p. D2) The Southern Ocean around Antarctica was once warmer. Then about 30 million years ago, the temperature dropped. Few fish could survive temperatures that were just above seawater’s freezing point, and they either migrated to warmer waters or went extinct.

One bottom-dweller held on. Through the power of natural selection, its descendants developed traits that let them survive these unlikely conditions. Today, the Antarctic blackfin icefish, or Chaenocephalus aceratus, thrives in these frigid waters with no scales, blood as clear as water and bones so thin, you can see its brain through its skull.

For the full story see:

JoAnna Klein. “Skullduggery: It’s Not Hard to See How His Brain Works.” The New York Times (Tuesday, March 5, 2019 [sic]): D2.

(Note: the online version of the story has the date Feb. 28, 2019 [sic], and has the title “How the Icefish Got Its Transparent Blood and See-Through Skull.”)

The article quoted above references the following academic article:

Kim, Bo-Mi, Angel Amores, Seunghyun Kang, Do-Hwan Ahn, Jin-Hyoung Kim, Il-Chan Kim, Jun Hyuck Lee, Sung Gu Lee, Hyoungseok Lee, Jungeun Lee, Han-Woo Kim, Thomas Desvignes, Peter Batzel, Jason Sydes, Tom Titus, Catherine A. Wilson, Julian M. Catchen, Wesley C. Warren, Manfred Schartl, H. William Detrich, John H. Postlethwait, and Hyun Park. “Antarctic Blackfin Icefish Genome Reveals Adaptations to Extreme Environments.” Nature Ecology & Evolution 3, no. 3 (March 2019): 469-78.