Uploaded June 2017 | Updated September 2026, 2 weeks ago
Risso’s Dolphin Facts
HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.
It is a very robust dolphin, devoid of a snout. If only its dorsal fin appears above the surface of the ocean, it can be confused with a bottlenose dolphin (Tursiops truncatus) or with an orca (Orcinus orca), since the shape of its fin resembles that of orcas and Tursiops truncatus.
Weight and size.
The length of its body is on average 3 meters, but some individuals reach up to 4.3 meters. It has a body mass of 300 to 500 kilograms.
Morphology.
This dolphin has a compact and almost square head, similar to that of pilot whales (Globicephala Family), and it also lacks a beak. The anterior part of the body is sturdy but narrows towards the tail. Its dorsal fin with a sickle shape is large and curved, located in the center of the back. The pectoral flippers are long and thin and bent backward in a semi-straight line. The caudal peduncle is very narrow.
Skin Coloration.
It varies according to the age of the dolphin. Young specimens have a metallic gray or brown skin in the dorsal area and whitish in the belly. The snout has an ocher color, and between the pectoral flippers, there is a light spot with an anchor shape. As they grow, the coloration fades, and the adults appear to be almost white. They have 2 to 7 pairs of teeth in the lower jaw
Distinctive characteristics.
Its superior jaw is devoid of teeth, and on the melon, there is an external vertical groove that extends from that organ to the mouth. Another distinctive sign of the species is the presence of scar marks on the back and sides due to a lack of repigmentation and a very slow healing process.
WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.
This dolphin has a wide distribution in temperate, tropical and subtropical waters of the oceans of the world between the latitudes 60° north and 55° south. In the northern hemisphere, Scotland is the limit of its distribution, and in the southern hemisphere, it does not travel beyond the Cape of Good Hope, Australia, and New Zealand. Its distribution zones include the Gulf of Alaska, the Gulf of Mexico, the Persian Gulf and the Red Sea.
The countries that host the species include: Australia, Bahamas, Barbados, United Kingdom, United Arab Emirates, Peru, Philippines, Papua New Guinea, Madagascar, Mexico, Chile, China, Canada, United States, Cook Islands, Brazil, Cayman Islands, Argentina, Costa Rica, Haiti, India, Indonesia, Japan, Jamaica, Mozambique, Denmark, Ecuador, New Zealand, Taiwan and France.
It prefers to inhabit deep waters of the continental slope and seldom ventures to visit the coastal areas. It avoids polar waters and likes those with temperatures between 15° to 20° Celsius but can thrive in waters up to 10° Celsius. It dwells on steep slopes, edges of the continental shelf, mountains and submarine canyons.
WHAT DO THEY EAT? DIET AND EATING HABITS.
The daily diet of the Risso dolphin is composed of fish, crustaceans such as krill and cephalopods such as squid, octopus, and cuttlefish. Thier favorite food is Argonauta argo, a species of pelagic octopus.
Usually, they seek their food at night when the prey travels to the surface of the ocean, but they can submerge to depths less than 1,000 meters (their usual range is 600-800 meters) for 30 minutes to get food. Occasionally they feed in cooperation with other dolphins.Their teeth only serve to hold their prey firmly, as this dolphin swallows its victims whole.
HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.
It is very likely that Risso’s dolphin reproduces throughout the year but with regional variations. In southern Africa, for example, births occur mainly during December.
The breeding practice is not known, but the hypotheses focus on polygamy and multiple mating during the same season (polyandry). The gestation period lasts between 13 and 14 months; Subsequently, only one offspring of about 20 kilograms of weight is born.
The mother cares the calf until it leaves the pod, a few time after being weaned at 12-18 months of age.
Females mature sexually at the age of 8 to ten years, but males reach maturity around 10 and 12 years of age. Mothers give birth every 2.4 years.
Risso’s Dolphin Facts
HOW DO THEY LOOK? PHYSICAL CHARACTERISTICS.
It is a very robust dolphin, devoid of a snout. If only its dorsal fin appears above the surface of the ocean, it can be confused with a bottlenose dolphin (Tursiops truncatus) or with an orca (Orcinus orca), since the shape of its fin resembles that of orcas and Tursiops truncatus.
Weight and size.
The length of its body is on average 3 meters, but some individuals reach up to 4.3 meters. It has a body mass of 300 to 500 kilograms.
Morphology.
This dolphin has a compact and almost square head, similar to that of pilot whales (Globicephala Family), and it also lacks a beak. The anterior part of the body is sturdy but narrows towards the tail. Its dorsal fin with a sickle shape is large and curved, located in the center of the back. The pectoral flippers are long and thin and bent backward in a semi-straight line. The caudal peduncle is very narrow.
Skin Coloration.
It varies according to the age of the dolphin. Young specimens have a metallic gray or brown skin in the dorsal area and whitish in the belly. The snout has an ocher color, and between the pectoral flippers, there is a light spot with an anchor shape. As they grow, the coloration fades, and the adults appear to be almost white. They have 2 to 7 pairs of teeth in the lower jaw
Distinctive characteristics.
Its superior jaw is devoid of teeth, and on the melon, there is an external vertical groove that extends from that organ to the mouth. Another distinctive sign of the species is the presence of scar marks on the back and sides due to a lack of repigmentation and a very slow healing process.
WHERE DO THEY LIVE? DISTRIBUTION AND HABITAT.
This dolphin has a wide distribution in temperate, tropical and subtropical waters of the oceans of the world between the latitudes 60° north and 55° south. In the northern hemisphere, Scotland is the limit of its distribution, and in the southern hemisphere, it does not travel beyond the Cape of Good Hope, Australia, and New Zealand. Its distribution zones include the Gulf of Alaska, the Gulf of Mexico, the Persian Gulf and the Red Sea.
The countries that host the species include: Australia, Bahamas, Barbados, United Kingdom, United Arab Emirates, Peru, Philippines, Papua New Guinea, Madagascar, Mexico, Chile, China, Canada, United States, Cook Islands, Brazil, Cayman Islands, Argentina, Costa Rica, Haiti, India, Indonesia, Japan, Jamaica, Mozambique, Denmark, Ecuador, New Zealand, Taiwan and France.
It prefers to inhabit deep waters of the continental slope and seldom ventures to visit the coastal areas. It avoids polar waters and likes those with temperatures between 15° to 20° Celsius but can thrive in waters up to 10° Celsius. It dwells on steep slopes, edges of the continental shelf, mountains and submarine canyons.
WHAT DO THEY EAT? DIET AND EATING HABITS.
The daily diet of the Risso dolphin is composed of fish, crustaceans such as krill and cephalopods such as squid, octopus, and cuttlefish. Thier favorite food is Argonauta argo, a species of pelagic octopus.
Usually, they seek their food at night when the prey travels to the surface of the ocean, but they can submerge to depths less than 1,000 meters (their usual range is 600-800 meters) for 30 minutes to get food. Occasionally they feed in cooperation with other dolphins.Their teeth only serve to hold their prey firmly, as this dolphin swallows its victims whole.
HOW DO THEY REPRODUCE? MATING AND REPRODUCTION.
It is very likely that Risso’s dolphin reproduces throughout the year but with regional variations. In southern Africa, for example, births occur mainly during December.
The breeding practice is not known, but the hypotheses focus on polygamy and multiple mating during the same season (polyandry). The gestation period lasts between 13 and 14 months; Subsequently, only one offspring of about 20 kilograms of weight is born.
The mother cares the calf until it leaves the pod, a few time after being weaned at 12-18 months of age.
Females mature sexually at the age of 8 to ten years, but males reach maturity around 10 and 12 years of age. Mothers give birth every 2.4 years.
