Risso’s Dolphin

Risso’s Dolphin Facts

• Risso’s Dolphin serves as the common name for the rather adorable Grampus griseus. It’s not only pleasing to the eye, it also ranks among the largest of all known types of dolphin.
• However, and quite unfortunately, the animal has not been widely studied. This regrettable fact occurs due to its strong preference for inhabiting deep ocean waters. This makes studying it difficult.
• Further, people, including scientists, once thought this incredible variety of dolphin to be quite rare. This held true because of the simple fact that sightings of it occurred extremely rarely.
• Thankfully, evidence now indicates that it remains (surprisingly, given man’s hunting habits) present in great numbers. Furthermore, it appears to be present throughout many of the world’s oceans.
• Finally, as many as 30,000 of the Grampus griseus appear to inhabit one specific area alone. That region consists of the ocean waters adjacent to the coast of California, United States.

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Source: http://bit.ly/2FwzY4x Photographer: Mike Baird CC License: http://bit.ly/2xQPH8p

Risso’s Dolphin Physical Description

Sexual Dimorphism is present among the Risso’s Dolphin, but only to a small extent. The males grow slightly larger, attaining a length of as much as 12.5 ft (3.8 m). These sometimes weigh as much as 1,100 lb (500 kg). However, these average only about 659 lb (300 kg). 

The flippers also grow comparatively long and slender in shape. The head is also much more rounded than that of most dolphins. Further, it has a distinctive crease in the sonar-detecting organ known as the melon.

In addition, its natural coloring shows primarily a dark gray. However, adults often display extensive white patches. These occur as a result of scarring from encounters with prey and potential predators.

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Artiodactyla
• Family: Delphinidae
• Genus: Grampus
• Species: G. griseus

Risso’s Dolphin Distribution, Habitat, and Ecology

Firstly, the truly fascinating Risso’s Dolphin primarily inhabits the warm waters of the world. The impressive animal also appears to primarily inhabit regions near continental shelves.

The Grampus griseus seems to be a long-lived cetacean species, compared to other, related species. As a result of this longer lifespan, many individuals appear to live as long as 40 years.

Additionally, a typical group of this type of dolphin (known as a pod) usually contains as many as 30 individuals. Yet, some super-pods occasionally contain as many as 4,000 specimens. 

It will also feed on a wide variety of fish species, being opportunistic in nature. However, its favorite prey is small species of squid, also native to most of the areas that it inhabits.

Finally, though information is scarce, the Risso’s Dolphin appears to have few natural predators itself.

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