We are told that 200 genera of fish glow, and a 2016 study reported that bioluminescence “has arisen independently at least 27 times in marine fishes” (convergent evolution). At first, colleagues were understandably skeptical that one fish just eats and runs with luciferin (the basis of bioluminescence).
Scientists have hypothesized that bioluminescent fish make their own luciferase, the enzyme that catalyzes the reaction that causes luciferin to glow. But in a study published this week (January 8) in Science Advances, researchers showed that a species of coastal fish generates light using both luciferin and luciferase captured from its bioluminescent prey, a small crustacean known as an ostracod…
Previous work had shown that fish in the genus Parapriacanthus, shallow-water fish found off the coast of the west Pacific and Indian Oceans, sequester luciferin from their prey in their light organs, but it was believed that they were making their own luciferase enzyme. So when Bessho-Uehara and his colleagues in Japan looked for a luciferase gene in the Parapriacanthus ransonneti genome, they expected to find a fish gene encoding a fish protein. Instead, they discovered that the luciferase protein in the light organs that run along the underside of the fish was identical to the enzyme produced by the ostracods these fish eat.Abby Olena, “Fish Steals Bioluminescence from Prey” at The Scientist
Note: This is not horizontal gene transfer; the fish are eating and repurposing the enzymes rather than incorporating the genes for producing them. But if the fish can in fact steal the enzymes, that’s something to keep in mind as we hear evolutionary biologists explain to us how this and other traits evolved via natural selection acting on the random mutations of the fish’s genome (Darwinism)…
See also: Horizontal gene transfer: Sorry, Darwin, it’s not your evolution any more
Evolution appears to converge on goals But how is that possible?