Exposure to Sunlight Gives Sharks a Tan

NEW YORK — Even sharks can get a suntan.

In a Hawaiian bay that acts as a nursery for scalloped hammerhead sharks, young sharks change from light tan to dark brown or black over several weeks if they are held in a shallow pond.

Since human skin becomes tan from an accumulation of a pigment called melanin, the researchers studied melanin concentrations in the pectoral fins of young sharks in the pond. They found that melanin concentrations rose by 14% during three weeks to exposure to sunlight and 28% over 215 days.

The finding may be handy for medical research because sharks don’t appear to get skin cancers, which in people are caused by too much exposure to the sun, researchers from the University of Hawaii in Kaneohe wrote in the Oct. 24 issue of the journal Nature.