If you were a fearsome predator like a shark – patrolling the waters ready to find and kill prey - your advantage would come by camouflaging into the colours of the water – and being that classic grey colour.

You wouldn’t want to announce your arrival by being bright orange!

But this is what has happened to a nurse shark, Ginglymostoma cirratum, found in the waters off the coast of Costa Rica. Check out the link below to see a photo of it – it had white eyes too. This is not your normal one mutation deal but a combination of very rare mutations of abnormal pigmentation. One mutation is that of albinism – where there is no dark pigmentation but the second mutation is that of xanthism – where there is an excess of yellow pigmentation. This combined set of mutations is called albino-xanthochromism and extremely rare.

Quite remarkably this individual has not been selected against by the selection pressure of finding prey or being eaten by a predator, like a tiger shark. This individual was fully mature and probably over 10 years old.

Mutations are random and spontaneous events that change the DNA base sequence. Sometimes they result in a selective advantage and drive natural selection and evolution. Sometimes they are harmful, usually resulting in the individual being selected against. Many mutations are neutral events so don’t affect selection. The probability of these two rare mutations occurring in the same individual is very low indeed and then the probability of this individual surviving is even lower.

Download the article from the Sciencealert page here