Why are fish more colourful in warmer waters?

[Deefstes]

Can someone explain to me if there is a scientific explanation as to why fish in warmer waters are generally more colourful than those in colder waters?

Similarly, and I'm not sure if this is a universal truth, but at least in South Africa it would seem that plantlife is generally more colourful in colder waters than in warmer waters. Any explanation for this?

 

[maged_mmh]

for the fish part, i think it is to blend in easily with their habitat (coral reefs).
never been diving in cold climates though.

 

[tridacna]

Can someone explain to me if there is a scientific explanation as to why fish in warmer waters are generally more colourful than those in colder waters?

Similarly, and I'm not sure if this is a universal truth, but at least in South Africa it would seem that plantlife is generally more colourful in colder waters than in warmer waters. Any explanation for this?

Easy answer in South Africa. For many years, the SA government had a policy of separate development and habitation. Lighter colored fishes were prevented from mixing with their darker colored brethren. As you know, this artificial barrier was eliminated resulting in a new spectrum of spectacular rainbow colored fishes.

Or perhaps, fish coloration may simply be a Darwinian response to their zoothanthellae dominated environment.

I've dived in SA, Mauritius, Seychelles. Also Indonesia, Red Sea and Australia. I never found the SA fish to be more colorful than those locations. OTOH the Caribbbean does not have nearly the same diversity of color as do the others. (Wait - they have more drab corals and plants too - see any correlation?). For more information see "Origin of Species - Charles Darwin".

 

[Deefstes]

I'm not saying the fish in South Africa are generally more colourful than those of Indonesia, Australia or wherever. I'm pretty sure they're not.

What I am saying is that it appears that fish of warmer waters are generally more colourful than those in colder waters. From my South African frame of reference I can only compare the fish found along the northern Natal coast to those found around the Western Cape. I have never dived there but I can only imagine that, in Australia, the fish found along the Queensland coast will be more colourful than those found around Perth. Or in the USA you'll find more colourful fish around the Florida Keys than you will around New England.

 

[tuner fish]

The fish in the deepest darkest coldest parts of the ocean are often brilliant red. Why? diet, camoflage as red is the first color to dissapear underwater. I don't think you will find a simple answer.

 

[drbill]

The classic explanation I've heard since college (in the Dark Ages) is that due to the higher species diversity and generally lower numbers of each species in the tropics, critters need to stand out and be identifiable for purposes of mating. Color is one way to make yourself more obvious for that purpose. Behavior and chemical pheromones are other ways. Owning a racy sports car and flashing a roll of thousand dollar bills doesn't work as well down under (and I certainly get nowhere fast with the mermaids by driving my golf cart and flashing a roll of pennies).

 

[Deefstes]

Haha. Well thanks, that makes pretty good sense.