Home » Plants & Animals » Dolphins » Dolphin Feature - The Risso Dolphin

Dolphin Feature - The Risso Dolphin

© Carma Haley Shoemaker

When the word "dolphin" is heard, most envision a sleek, silver-gray body with a long beak and the ever-present smile of the well-known bottlenose dolphin. As shown with previous dolphin feature articles, this is not always a proper description. The Risso dolphin is just one example of the various size and body shape that a dolphin may posses.

An Italian amateur naturalist named Risso first identified this species of dolphin, the Grampus griseus, in 1811. The dolphins he observed were off the coast of Africa, but Risso's dolphins are also found worldwide in deep tropical and temperate waters. Risso, after drawing the species to the best of his ability, sent a written description and pictures to a famous French anatomist who recorded the species, and named it after the man who documented the first information on it, Risso.

Measuring up to thirteen feet in length at adulthood, the Risso dolphin has a "robust" body, melon shaped head, and no beak. Both the flippers and the dorsal fin are dominant and pointed. The dorsal fin of the Risso dolphin can be as long as two feet in length. Infant Risso dolphins are light gray in color and will change to the brown tint as they grow and mature. Risso dolphins tend to be covered with various scars and scratches on their bodies. These are thought to be from the "mating" rituals and play that occurs between the species daily which, at times, can become rather intense and violent.

Another unique feature of the Risso dolphin is the absence of teeth in the upper jaw. There are between 2 and 7 pairs of peg-like, rounded teeth in the lower jaw which most Risso's will lose during their adult life. Due to the decreased number of teeth, and the shape of the present teeth, the Risso dolphin's diet mainly contains squid and octopi. In the event of a decreased number of their normal prey, the Risso has been known to take various fish while feeding.

The Risso dolphin will live his existence in family pod. These pods can contain anywhere from 3 to 50 individuals. However, as with other species, at times the pods will aggregate and the numbers of Risso's that can be viewed together can be as high as 4,000. The dolphins will swim and surface in a series, or straight-line, formation. It is not uncommon to see these dolphins jumping, breaching, and bowriding. Risso dolphins use the familiar clicks, whistles and blowing as other dolphin species also do.

The copyright of the article Dolphin Feature - The Risso Dolphin in Dolphins is owned by . Permission to republish Dolphin Feature - The Risso Dolphin in print or online must be granted by the author in writing.