About Risso's Dolphins

Risso’s dolphins, which are named after the man who first described them, are rarely seen inshore where waters are shallow. Risso's inhabit deep, temperate waters worldwide. This species of dolphin (Grampus griseus) is a medium-sized dolphin that is sometimes compared to pilot whales because of their similar rounded head and stocky body shape. Around the world, Risso’s dolphins are seen along the Continental Shelf and Continental Slope.

Risso’s dolphins are unique because of the white scarring on their bodies that increases with age. Wild dolphins often receive scars after normal interactions with other dolphins, predators and sometimes even their prey. In other species, the scars are colored over with the animal’s natural pigment. But in Risso’s dolphins, the pigment does not return to the scarred area and, over time, the animal takes on a lighter or even white color.

These individually-distinctive scarring patterns have helped researchers in places such as Monterey Bay, Ca., identify individuals in the wild.