Tuesday, March 16, 2021

Sharks That Glow in the Dark

Environmental & Science Education, STEM, Behavior, Ocean, Biological Evolution, Wildlife

Ed Hessler

An article in The Guardian by Elle Hunt calls our attention to yet another species--no, three--that glow in the dark. One "is now the largest-known luminous vertebrate." 

"Bioluminescence--the production of visible light through a chemical reaction by living organisms--is a widespread phenomenon among marine life," Hunt writes, but this is the first time it has been documented and analysed in the kitefin shark (Dalatias licha), the blackbelly lanternshark (Etmopterus lucifer), and the southern lanternshark  (Etmopterus granulosa). The sharks were collected...from the Chatham Rise off the east coast of New Zealand. ... The Kitefin, which can grow to 180 cm (5.7 feet) , is now the largest-known luminous vertebrate: what the research team referred to as a 'giant luminous shark'".

The researchers have some ideas about how this luminosity may be used by the glowing sharks. For two of them it may be as camouflage "against the bright surface of the water. The kitefin shark is not known to have any predators, is slow-moving so the glow might be used "to illuminate the sea floor while it searches for food, or to disguise itself while approaching prey." All three inhabit what is known as the "'twilight' zone of the ocean, between 200 (~ 656 feet) and 1000 meters (~3280 feet) deep, beyiond which sunlight does not penetrate."

Hunt's article includes a photograph as well as a link to the original paper in which the findings were reported.


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