This species of dolphin takes its name from Antoine Risso, the first man to offer a description of the animal which was later released publicly. Risso’s dolphin has a relatively stocky body and a large dorsal fin, but narrows down to a very slender tail. Their most identifiable feature is their bulbous head which lacks a protruding beak.
When they are first born, Risso’s dolphins are a grey-ish brown color with cream bellies and an anchor-shaped mark on the side of their face. As the calf grows older, the grey- ish brown darkens to become nearly black for a short period of time, before reverting back to grey when the dolphins reach maturity.
As the Risso’s dolphins reach later adulthood they become much lighter in color and turn almost white. Throughout the course of their lives they collect linear scars vertically along the length of their body. These scars are accumulated from various interactions with dolphins of the same species.
Risso’s dolphins are typically around 10 feet in length, although there have been individuals recorded at over 13 feet long. As with most species of dolphin, the males tend to be larger and longer than the females. They usually reach between 660 and 1100 lb, making the Risso’s dolphin the second largest species in the dolphin family.
Risso’s dolphins are found all over the world in both temperate and tropical waters. They don’t tend to stray too far from land but prefer to live in deep waters. They are seen regularly in tropical areas in the Indian, Atlantic and Pacific Oceans. They are also often sighted in the Persian Gulf, Red Sea and the Mediterranean. They have a wider range than many other species of dolphin and can be seen as far north as Alaska and the south coast of Greenland and swim down south to Tierra del Fuego.
The conservation status of Risso’s dolphins is at ‘least concern’; their habitats and food sources are not threatened and they are in no danger of extinction. Their diet consists almost entirely of squid and they tend to feed during the night. They tend to travel in groups of between 10 and 50 dolphins but have been spotted swimming with more than 400 dolphins at a time. Risso’s dolphins have a gestation period of 13 – 14 months and females deliver a single calf every two and a half years or so.