Risso’s Dolphins (Grampus Griseus) are the only dolphins in the genus Grampus; their name was derived from Niçard naturalist, Antoine Risso.
They are a relatively large dolphin species, with adult lengths averaging at around 10′ and some individuals can grow over to be 13′. They don’t look like a “typical” dolphin, as they have a blunt shaped head and don’t have a long, protruding beak.
Risso’s dolphins can be highly active at the surface exhibiting a range of behaviours like breaching and spyhopping. They usually do not bow ride, but they can be seen travelling in the wake of ships.
Younger Risso’s are usually darker in color and older individuals appear more white. When they are born, infants are dark grey on their sides and back, with cream colored areas on their bellies and around the beaks. In older calves, the nonwhite areas darken to nearly black, and then lighten (except for the always dark dorsal fin).
As they grow older, white linear scars begin to cover their bodies. These are derived from scratches from squid (their primary prey) and from other Risso’s dolphins during social interaction; these scars eventually cover the bulk of the body, hence why older individuals appear whiter.
Most individuals have two to seven pairs of teeth, all in the lower jaw. Rather than teeth in the upper jaw, there are “sockets” that fit each tooth on the lower jaw. This is a common characteristic for cetacean that feed heavily on squid (i.e. Sperm Whales).
They are found worldwide, in temperate and some tropical waters. They typically reside in deep water, fairly close to land. Here in Southern California, we see them once or twice every few months. They are considered to be one of the 5 most commonly seen local dolphin species (the others are Long and Short beaked Common Dolphin, Bottlenose Dolphin and Pacific Whitesided Dolphin).
I didn’t get to see any orcas today, even though the other boat spotted a lone male that disappeared into the fog, but that’s okay. I got to see about 10 humpbacks throughout the day, culminating in an hour-long lunge-feeding session at the end of the day. We also saw pods of Risso’s and Pacific White-sided dolphins. It’s no wonder why Monterey is my favorite place to whale watch - I’ve never been disappointed. 😊
Earlier this dolphin drive and slaughter season, which has now ended, two white Risso’s dolphins were netted with their pods and then captured for captivity while their families were slaughtered for meat. Neither are albinos since they have black spots on their bodies.
Both Risso’s have now gone on public display at Taiji Whale Museum as of March 14, 2015. The Museum is also taking votes for names from visitors to the park.
It also appears the pie-bald was mis-sexed when originally captured; both Risso’s are now noted as males. Good thing they cannot be bred since they are the same gender. #DolphinAwarenessMonth
Source: Ceta Base
you seen them? Pods
of Risso’s dolphins have been gliding past the Aquarium this week! You can
identify these distinct cetaceans by the scarring they get from tussling with
squid and other cephalopods–their favorite food. Thanks to Jim Capwell for the photo!
Seeing whales in the wild where they belong is the most amazing thing to witness. It cost me $40 for a ticket to go on a 3 hour tour off the coast of California. $40 well spent. I saw Gray Whales, Rissos Dolphins, Sea Otters, Sea lions, seals and Pelicans!
Please consider this alternative rather than visiting Sea World. It isn’t that much of a price difference for the entire trip trust me. It’s also well worth it. You won’t be disappointed.
See all these beautiful animals in their natural environment.. the ocean.. their home! All of these photos were taken from the same tour I was on but at different times of the year.
The hunters in Taiji rounded up and killed a pod of four Risso’s dolphins today.
At that point, it’s not even economically sensible - the time, effort and resources used to herd in this small family and slaughter them all was likely not made up for by whatever they gain from killing them.