The functional significance of colouration in cetaceans

Cetaceans show many of the classic mammalian colouration patterns, such as uniform colouration, countershading, and prominent patches of colour, all within one relatively small taxon. We collated all the functional hypotheses for cetacean colouration that have been put forward in the literature and systematically tested them using comparative phylogenetic analyses. We found that countershading is a mechanism by which smaller cetacean species may avoid being seen by their prey. We discovered that prominent markings are associated with group living, fast swimming, and ostentatious behaviour at the surface, suggesting that they function in intraspecific communication. White markings on several parts of the body seem to be involved in the capture of fish, squid, and krill. Therefore, several different selection pressures have shaped the great diversity of skin colouration seen in extant cetaceans, although background matching, disruptive colouration and interspecific communication do not appear to be involved.