Natures wonders: many species glow in deep ocean (Introduction)

by David Turell @, Wednesday, December 28, 2016, 21:44 (1155 days ago) @ David Turell

Complex biochemistry keeps organisms glowing in the deep ocean. How it works:

"Though some of the most familiar examples of light from living organisms are terrestrial — think of fireflies, glowworms and foxfire — the bulk of evolutionary events involving bioluminescence took place in the ocean. Bioluminescence is in fact markedly absent from all terrestrial vertebrates and flowering plants.

"In the deep ocean, light gives organisms a unique way to attract prey, communicate and defend themselves, said Matthew Davis, a biologist at St. Cloud State University in Minnesota. In a study released in June, he and his colleagues found that fish that use light for communication and courtship signaling were especially diverse. Over a period of about 150 million years — brief by evolutionary standards —such fish proliferated into more species than other groups of fish. Bioluminescent species that used their light exclusively for camouflage, on the other hand, were no more diverse.


"In nearly all shining organisms, bioluminescence requires three ingredients: oxygen, a light-emitting pigment called a luciferin (from the Latin word lucifer, meaning light-bringing), and an enzyme called a luciferase. When a luciferin reacts with oxygen — a process facilitated by luciferase — it forms an excited, unstable compound that emits light when it returns to its lowest energy state.

"Curiously, there are far fewer luciferins than luciferases. While species tend to have unique luciferases, many share the same luciferin. Just four luciferins are responsible for most of the light production in the ocean. Of close to 20 groups of bioluminescent organisms in the world, a luciferin called coelenterazine is the light-emitter in nine.


"It’s more likely that many of these species don’t make coelenterazine themselves. Instead, they get it from their diet, said Yuichi Oba, a professor of biology at Chubu University in Japan.

"In 2009, a group led by Oba discovered that the deep-sea copepod — a tiny, near-ubiquitous crustacean — makes its own coelenterazine. These copepods are an extremely abundant food source for a wide range of marine animals — so much so that “in Japan, we call copepods ‘rice in the ocean,’” Oba said. He thinks copepods are key to understanding why so many marine organisms are bioluminescent.

"Oba and his colleagues took amino acids believed to be the building blocks of coelenterazine, labeled them with a molecular marker, and loaded them into copepod food. They then fed this food to copepods in the lab.

"Even the jellyfish in which coelenterazine was first discovered (and named after) was later found not to produce its own coelenterazine at all. It obtains its luciferin by eating copepods and other small crustaceans.

"After 24 hours, the researchers extracted coelenterazine from the copepods and looked for the labels they had added. Sure enough, the labels were there — definitive proof that the crustaceans had synthesized luciferin molecules from the amino acids."

Comment: This study shows the importance of the food chain in the balance of nature. further, one wonders how this system developed. Granted oxygen existed and could be used, but luciferin had to be discovered by evolution and luciferase developed. Remember the point that luciferase as an enzyme is a huge molecule with a necessary shape for function. Evolution had to find this particular molecule also. They must have been developed contemporaneously. More evidence of a saltation.

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