SoylentNews

MrPlow writes:

Submitted via IRC for Runaway1956_

Some fishes in the deep, dark sea may see their world in more than just shades of gray.

A survey of 101 fish species reveals that four from the deep sea had a surprising number of genes for light-sensitive eye proteins called rod opsins, researchers report in the May 10 Science. Depending on how the animals use those light catchers, the discovery might challenge the widespread idea that deep-sea fishes don't see color, says coauthor Zuzana Musilová, an evolutionary biologist at Charles University in Prague.

To see, many fishes, humans and most other vertebrates rely on two types of light-detecting cells in the eye known as rods and cones. Cone cells use two or more kinds of opsins and need decent amounts of light to work. Rods generally use only one opsin called RH1, which works in dim light. That variety in opsins in cones, but not in rods, lets vertebrates see a range of colors in well-lit conditions but be color-blind in the near dark.

In the new study, Musilová and Fabio Cortesi of the University of Queensland in Brisbane, Australia sailed on research ships equipped to reach into the ocean depths for fish. The deep-sea specimens came from the "twilight" zone 200 to 1,000 meters below the surface, where sunlight becomes only a subtle lessening of darkness. The most colorful things to look at would be bioluminescent spots on animals' bodies.

The four deep-sea fishes with the special eyes came from three different lineages that had independently evolved genes for more than one kind of RH1 rod opsin, Musilová, Cortesi and their colleagues report. A glacier lantern fish (Benthosema glaciale) had genes for five different forms of RH1, and a tube-eye (Stylephorus chordatus) had six. Two kinds of spinyfin had even more, 18 genes for the longwing spinyfin (Diretmoides pauciradiatus) and a stunning 38 for the silver spinyfin (Diretmus argenteus).

Source: https://www.sciencenews.org/article/deep-sea-fish-eye-chemistry-might-let-them-see-colors-near-dark

Original Submission