Bats and Melatonin - why are bats not white or uncolored?

Question

I'm not a biologist  but I know a few things. 
1. Melatonin is a chemical that makes living things colored,  like the skin or fur  of animals, the color of our eyes, and even the colors  of  plants.  It protects  us from the sun, and, in animals, makes colorful patterns to attract a mate. 

2. Animals that have evolved living in caves often have no color at all, they are often white or even transparent. Apparently they have no need for the protection of melatonin from the sun, and, because they are blind, no benefit from color to attract a mate. There is apparently some cost in investing in melatonin from an evolutionary point of view. 

3. Many bats live in caves and only come out at night. They are blind. 

So here is my question: 
Why are most bats a dark color, usually dark brown?

Anonymous · Accepted Answer

Aside from your melanin/melatonin confusion and the blindness bit, your thinking is fairly sound. However, the white cave animals are ones that spend their entire lives in caves. Bats fly around outside, mostly in the evenings and white fur would make them stand out too much.

Skwerl · Answer

1. Melanin. Melatonin is a sleep-regulating chemical.
3. Bats are not blind, but at there speed and size, echolocation is a more effective navigational aid while flying.


As for their color, color is an effect of light reflection. When something is green, that means that the object absorbs most of the other colors, but reflects the green wavelengths. White is the combination of all/most visible wavelengths, and black is the absence thereof. Bats are black or other dark colors because they absorb most of the visible spectrum of light. Melanin does help color, but only because the chemical is effective at light absorption and reflection. Other chemicals do the same thing. And the lack of color does not necessarily mean that an animal has no melanin.

Anonymous · Answer

Bats are NOT blind and never have been.  Also, they don''t live in caves all the time...rather they may roost in them during the day, but bats feed all night.  Also, some bats don't roost in caves at all, some species roost in trees, and on the eaves of porches, in bridges, in rock crevices, and even in leaf litter. They come out to feed each night and if they were white they would be extremely vulnerable as they would be easily seen by predators such as owls.

earwig · Answer

couple of points:

1. Fruit bats do have pretty good vision.
2. Nothing can be called uncoloured.
3. Dark coloration in bats could have come about as a defense against predators (crypsis or camouflage).

? · Answer

bats are not blind, huge misunderstanding. they don't have the best eyesite, so they will use ecolocation. also there is a such thing as an albino bat. very rare, ranging from the yukatan to venezuala. other bats have color to disquise them at night when they come out of the caves at night to feed. also, color is based off of lights that bounce off the item. to create colors.

Bats and Melatonin - why are bats not white or uncolored?

5 Answers