Fishes in Sleep — Changing Color for Protection

1907

In Most Species They Experience a Change of Color

The way fishes sleep is a study which few people have taken up, but which is nevertheless very interesting. They are very light sleepers and frequently assume singular positions, but the most remarkable thing is the change of color which the majority of them undergo while asleep. Usually their spots and stripes become darker and more distinct when they have successfully sought temporary oblivion.

Sometimes the pattern of their coloring is entirely changed. The ordinary porgy, for instance, presents in the daytime beautifully iridescent hues playing over its silvery sides, but at night, on falling asleep, it takes on a dull bronze tint, and six conspicuous black bands make their appearance on its sides.

If it is suddenly awakened by the turning up of the gas in the aquarium it immediately resumes the silvery color that it shows by daylight. Naturalists ascribe these changes to the principle of "protective coloration" and point out that the appearance of black bands and the deepening of the spots serve to conceal the fish from their enemies when lying amid the seaweeds. — Buffalo Times.