Fish red fluorescence

Scientists have discovered that red is the preferred color for many fish species, and some species fluoresce in vivid colors.

Until now, many researchers have always assumed that red is a 'non-fictitious' color in the underwater kingdom, because the red wavelength of the sun is absorbed by near-seawater, according to Nico Michiels of Tübingen University. , Germany. He is the leader of the research team.

This means that objects that are red in the air or in shallow water will be gray or black at depths of less than 33 minutes (10 meters). Unlike red light, blue light penetrates deeper into the water, and that's why seawater is blue. However fish have found a way to get their favorite red.

Red fluorescence of finfish, or Enneapterygius pusillus, can be observed through the red buds (right).This fish has a gray color that is cloudy under natural light.(Photo: Nico Michiels et al)

New research results, published in the upcoming issue of BMC Ecology, show that 'red fluorescence is very common in marine fish species'.

Michiels discovered red fish accidentally by diving in Mangrove Bay in the Red Sea (the salty water between Africa and the Arabian Peninsula_ where he is studying the depth of red light that could be He went into seawater, he used special glasses that only allowed to see red, and he was surprised to see red spots around his eyes, running all over his body or covering a single fin of many. fish.

Michiels said: 'The most striking species of red around the eyes around the eyes or the whole body look like they glow.'

Fish of the wing, Pseudocheilinus evanidus (Labridae), radiate red light throughout the body.Fish image under natural light (left) and through red filter (right).(Photo: Nico Michiels et al)

Red light can be a private form of communication or an attractive signal, Michiels said, but he has no clear evidence yet. Because red light emanates from the fish itself, and is not filtered through the surface of the water, this phenomenon can easily be observed at close range.

Michiels told LiveScience: 'We believe we are the first to detect red fluorescence in fish, and see it as an important phenomenon in deepwater fish.'

Limestone algae, a species of Amphiroa, emits red fluorescence (right image) when viewed through a red filter.This is an algae that absorbs calcium from water to grow.(Photo: Nico Michiels et al)

Many fish species have shown their ability to fluoresce in blue and green. In 2005, a relative of the squid was identified as a red fluorescence species. (In fact, ink is not a fish).

Fluorescence occurs when light is absorbed at one wavelength and then emitted immediately at another wavelength. In the case of red rays, the fish absorbs blue light and then emits red light.

Michiels predicts that red fluorescence is a common phenomenon in deepwater fish as well as other fish. Since the first discovery so far, he has discovered several species that emit other light in the Mediterranean.