Risso's Dolphin

Overview

Risso's dolphins are distinctive, robust cetaceans easily recognized by their blunt, beakless heads and bodies heavily marked with white linear scars. They are a cosmopolitan species, inhabiting deep oceanic and continental slope waters across tropical and temperate regions worldwide.

Appearance

These dolphins possess a stout, torpedo-shaped body that tapers toward a narrow tailstock. A defining feature is the bulbous melon, which features a characteristic vertical crease running from the blowhole to the upper lip. Their coloration shifts significantly with age: calves are born with a uniform grey or brownish hue, but as they mature, they darken before eventually lightening. Older individuals often appear nearly white due to the accumulation of extensive, crisscrossing white scars, which are primarily caused by interactions with other members of their species and their prey.

Distribution & habitat

Risso's dolphins are widely distributed in both hemispheres, typically found between 64°N and 46°S. They show a strong preference for deep, offshore waters, particularly along the edges of continental shelves and steep slopes, often near submarine canyons. While they are primarily pelagic, they may occasionally venture into shallower coastal areas.

Biology & behavior

Highly social, these dolphins typically travel in pods of 10 to 50 individuals, though larger gatherings have been observed. They are known for their active surface behavior, including leaping, slapping their flippers or tails, and "spy-hopping" to observe their surroundings. They are also known to associate with other cetacean species.

Feeding

Primarily teuthophagous, their diet consists almost exclusively of cephalopods, such as squid, octopus, and cuttlefish. They are deep divers, capable of reaching depths of over 500 meters to forage, and they generally hunt at night when their prey is more active near the surface.