Risso's Dolphin (Grampus griseus)
These are robust animals with a torpedo-shaped body. The had has no beak and has a large rounded melon with a distinctive forehead.
They only have teeth in the lower jaw. Dorsal fin is high, falcate, and centrally located on the back. Pectoral fins, or flippers, are long, curved and pointed. They are born grey and dark blue, but they become lighter as they grow until they turn grey with many whitish lines. Males can reach 4 m, while females are no longer than 3.5 m. They can weigh from 250 to 400 kg.
They live in warm waters all over the world. They can usually be found in see and oceans with the surface temperature round 13ºC and 28ºC (55.4 ºF - 82.4 ºF).
How They Live
They tend to be in small groups of up to 50 individuals or live alone. They live in deep water and primarily feed off cephalopods, although they can also prey on small fish and crustaceans. While hunting, they can reach the cost, although this is not the habitat they prefer. These are rather active animals that can swim very fast and jump out of the water.
They are good divers that can spend more than half an hour under the water.
There is hardly any data related to their reproduction. When born, the young are round 1.4 m large.
Threats and Conservation Measures in Andalusia
Considering that they are unpredictable and prefer deep sea, they are rarely sighted in an uncontrolled way. However, there can be interactions between this species and fishing if the prey is the same. Moreover, unfortunately, they are also affected by toxic waste and litter on the coast.
This species conservation is based on the rules set by the international bodies such as the IUCN (International Union for Conservation of Nature) or the United Nations.
Places Where They Can Be Seen
Any encounter with a Risso's dolphin, dead or alive, will be a simple coincidence, as this species is rare on this coast even though it has been registered. In the museum Aula del Mar (the Sea Classroom), which is also a recovery centre, has registered several stranded dead animals and has had some of them under treatment for more than a week.
One of the most interesting features of this species are numerous marks and scars on their skin. Although one can think these are made by the nets and predators, they are mostly result of interactions with other individuals from this species and their preys.
Even though, adults can be confused with belugas due to their whitish colour in other parts of the world, on this coast, the only species which is similar to these dolphins as for its morphology is a long-finned pilot whale. However, their colour is different as the latter ones are dark coloured and larger.