Luminescent Pygmy Sharks: Evolutionary Origins?
By examining the bioluminescence of pygmy sharks, scientists believe they have found a clue as to how certain shark species evolved the ability to glow.
Pygmy sharks, at just 22cm long, are one of the smallest shark species in the world. Scientists found that the presence of the hormone prolactin turns off the pygmy shark’s bioluminescence, while in other glowing shark species this same hormone actually triggers their glow.
After examining this phenomenon, scientist suggested that pygmy sharks developed the ability to glow in shallow waters, while deeper water shark species evolved from there and developed a more advanced glowing ability.
Read more in the BBC article.