Risso's Dolphin Interesting Facts
What type of animal is a Risso's dolphin?
Risso's dolphins (Grampus griseus) are dolphins that fall in the whale and dolphin subfamily, commonly known as 'blackfish.' Other related animals in this subfamily are false killer whales long-finned pilot whales, melon-headed whales, pygmy killer whales, and short-finned pilot whales. Risso's dolphin taxonomy is Kingdom: Animalia, Order: Cetacea, Family: Delphinidae, Genus: Grampus, Species: griseus.
What class of animal does a Risso's dolphin belong to?
Risso's dolphins are aquatic mammals (Cetaceans) belonging to the family Delphinidae. They are the only dolphin species belonging to the genus Grampus. Other cetaceans are whales, dolphins, and porpoises. Their life is predominantly underwater; they breathe air and give birth to young ones.
How many Risso's dolphins are there in the world?
Risso's dolphins are distributed throughout the world. The exact population is unknown. According to Mediterranean Grampus Project, there are about 250 individuals in the western Pelagos Sanctuary. Another study in the western Ligurian Sea showed a decline in Risso's dolphin population size from 150 in 2005 to an average of 70–100 in 2014.
The latest population distribution of this species is in California, Oregon, Washington and the subpopulation estimates are at 16,066 dolphins. Hawaiian waters have 2,351 dolphins. In Sri Lanka there are 5,500-13,000 dolphins. Off the eastern Sulu Sea (Dolar), 1,514 dolphins were recorded. The eastern United States has 20,479 dolphins. In the northern Gulf of Mexico there are 2,169 dolphins, in Japan there are 83,300 dolphins and in the eastern tropical Pacific there are 175,000 dolphins.
Where does a Risso's dolphin live?
Risso's dolphins are distributed extensively throughout the subtropical, temperate and tropical waters. They are not found in shallow, enclosed bodies of water. These species have a cosmopolitan distribution across the Pacific Ocean, Atlantic Ocean, Indian Ocean, and the Mediterranean Sea. Risso's dolphins are found in areas like the Gulf of Alaska, Newfoundland, Gulf of Mexico, Monterey Bay California, Azores, Red Sea, Norway, Japan, and Russia in the Northern Hemisphere. They are known to inhabit the Mediterranean Sea. In the Southern Hemisphere, they are commonly found in Argentina, South Africa, Chile, Australia, and New Zealand. Risso's dolphins migrate seasonally from Northern Scotland to the Mediterranean during the winter and from Mexican waters to the coast of California during summer.
What is a Risso's dolphin's habitat?
Risso's dolphins are found in temperate and tropical water at a depth ranging from 1312-3937 ft (400-1200 m). These gray dolphins are pelagic and prefer steep slopes of continental shelf, seamounts, and submarine canyons. They prefer water temperatures of at least 50 F (10 C) and an average of 59–68 F (15–20 C).
Who do Risso's dolphins live with?
Risso's dolphins have a very social life and travel in groups of 10-50 dolphins. These animals are also found in pairs and as solitary individuals. Risso's dolphins interact with other whales and dolphins, like bottlenose dolphins, from time to time. Groups of dolphins are a school or pod.
How long does a Risso's dolphin live?
The average Risso's dolphin lifespan is between 20 and 30 years. The maximum recorded age in the wild was 35 years.
How do they reproduce?
Female Risso's dolphins attain sexual maturity by the age of 8-10 years. Risso's dolphin reproduction is sexual and gives birth to young ones. The gestation period of a Risso's dolphin is 13-14 months. They give birth only to one baby, Risso's dolphin at a time. Breeding happens year-round but is high during summer and winter. A baby dolphin nurses 12-18 months after being born and becomes a juvenile Risso's dolphin.
What is their conservation status?
According to the IUCN red list of Threatened Species, the conservation status of Risso's dolphins falls under the category of Least Concern (LC). They are not threatened or endangered but are protected under the Marine Mammals Protection Act. They often become by-catch of fishing. The fishing industry is notorious for the depletion of these dolphins and other related cetaceans.
Risso's Dolphin Fun Facts
What do Risso's dolphins look like?
Risso's dolphins are relatively stockier with a bulbous head that has a vertical crease on it. They have large dorsal fins that often mistake them for killer whales, bottlenose dolphins, and false killer whales. The flukes are broad and curved with a deep notch. Their flippers are long, thin, and pointed. The peduncle is very slender.
Unlike other dolphins, Risso's dolphin face doesn't have a beak. Baby Risso's dolphins are gray to brown with a cream color on the side. As they get older, the color gets darker, nearly black, and later lightens again. Linear white scars on Risso's dolphins cover their body as they grow older. This scaring supposedly occurs due to interaction with other dolphins and whales. It is also possible these scars came from parasites and due to their interaction with their preferred prey, squids. Risso's dolphins have a white anchor-shaped mark between their flippers.
How cute are they?
Dolphins are very adorable and playful species. They are highly intelligent and have the reputation of geniuses of the ocean. They look cute and cuddly.
How do they communicate?
Risso's dolphins communicate using echolocation. They produce sound waves that hit an object and reflect. They use echolocation for navigation, locating, and identifying prey and other objects in the water. The sound they make is known as clicks. The clicks of Risso's dolphins have a frequency of 65-72kHz. A unique ability of this species of dolphin is emitting sonar clicks while their forehead is above water. Other vocals include barks, grunts, whistles, buzzes, and pulse sounds. Whistles are also unique to Risso's species.
How big is a Risso's dolphin?
Risso's dolphin size ranges from 8.5-13 ft (2.6-4 m) in length. A male Risso's dolphin is slightly larger than a female dolphin.
How fast can a Risso's dolphin swim?
A Risso's dolphin can swim at an average speed range of 15 mph (24.14 kph). They spend the majority of their time traveling areas. They are active on the surface of the water by leaping and slapping their flippers.
How much does a Risso's dolphin weigh?
The weight of an adult Risso's dolphin ranges from 660–1,100 lb (300-500 kg).
What are the male and female names of the species?
A male Risso's dolphin is a bull, and a female is a cow.
What would you call a baby Risso's dolphin?
The baby dolphin Risso's is a calf.
What do they eat?
The preferred prey of Risso's dolphins is squids. They prey on bottom-dwelling organisms. Apart from squids (cephalopods), their main prey is fish, krill, and crustaceans. Greater Argonaut/paper nautilus is wild pelagic octopuses. Dolphins often chase them into shallow waters and feed on them. Risso's dolphin jaw has adapted with no teeth on their upper jaw and few pairs on the lower jaw to feed on squids. Risso's dolphin diet varies with their age and size.
Are they friendly?
Dolphins are well known for their friendly nature and are harmless to humans. This causes harm to them as they lose their instincts to escape and often become prey to vandals, hunters, and poachers. Compared to other dolphins, Risso's dolphins are fairly shy and timid.
Would they make a good pet?
Aquatic mammals are protected under the Marine Mammals Protection Act. It is illegal to keep any dolphins as pets. They are highly intelligent animals and are often compared to dogs for their behavior towards humans.
Did you know...
The white scars of Risso's dolphins are an indicator of the males' fitness during social interactions with them, other dolphins, and whales. Groups of Risso's dolphins consisting of 10-50 individuals have a stratified social structure. Groups are formed based on age and sex. They also occasionally form super pods consisting of groups of a few thousand individuals (4000 was recorded). Distributions of Risso's dolphins are spotted regularly in Monterey Bay, California, along with Pacific white-sided dolphins and northern right whale dolphins. A common parasitic species found on Risso's dolphins are sea lampreys.
'Ri-sōz' is Risso's dolphin pronunciation.
Sadly, Risso's dolphins are hunted for meat, oil, and fertilizers worldwide. Some are also poached for Risso's gray dolphin skull and live exhibitions. They often get caught on gill nets and become by-catch. Some individuals were also stranded on the coast over the years. In England, Risso's dolphins were considered a royal fish and exclusive property of the crown.
What is a Risso's dolphin's favorite habitat?
Risso's dolphin habitat is deep water that's beyond the continental shelves' edge. However, during summer, they frequent the shallow waters off Bardsey Island, North Wales.
What is strange about a Risso's dolphin's jaw?
Risso's dolphin's upper jaw is devoid of teeth. In the lower jaw, they have two to seven pairs of sharp teeth. They do not require cutting teeth to eat their prey. Their teeth are specialized to catch prey, compete for mates and food, and to fight predators.
Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! For more relatable content, check out these spinner dolphin facts and harbor porpoise facts pages.
You can even occupy yourself at home by coloring in one of our free printable Risso's Dolphin coloring pages.