For many, sharks are terrifying enough already, and a glow-in-the-dark shark is simply more than our nerves can handle.
Fortunately, the kite shark (Dalatias despite), now believed to be the world’s largest bioluminescent vertebrate, lives in the “twilight zone” at depths of 300 to 1,000 meters.
The five-foot-long shark was confirmed as a brilliant species in a recent study off the east coast of New Zealand. Bioluminescence is a well-established evolutionary phenomenon among deep marine life and it is not the first time it has been documented in sharks.
Confirmation that the kitefin does indeed emit biological light makes it the largest animal to display this characteristic.
But why would sharks, which we normally think of as ambush hunters, evolve to convey their position to the inhabitants of the mesopelagic zone?
The hypothesis of the corresponding study, published in Frontiers of marine science, suggests that what at first appears to be a way of lighting up and being seen is actually a kind of “backlighting” or camouflage.
For example, the kite shark feeds on the two species of lantern sharks analyzed in the study. Bioluminescent sharks, the study details, emit blue-green light when viewed at depths of about 450 meters, potentially breaking their shape and allowing them to go unnoticed.
For the hunter, this bioluminescence works like the stripes on a tiger or the scale pattern of a snake, allowing it to get close enough to prey species without being detected.
“Taking into account the immensity of the deep sea and the presence of luminous organisms in this area, it is now increasingly obvious that the production of light in depth must play an important role in structuring the largest ecosystem on our planet.” the researchers wrote.
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