Back to the sea, in this chapter we’ll talk about a marine mammal that, though being common in all the seas over the planet, is very particular in the Canary Islands. We are talking about the Risso’s dolphin (Grampus griseus), one of the cetacean species inhabiting our waters.
Text and photo: Alberto Sarabia Hierro
«Inhabiting» means, in the case of cetaceans, that their population has been regularly settled down for a long time, and this has been confirmed by different studies and researches in the archipelago for many years. Some of these species are the short-finned pilot whale (Globicephala macrorhynchus), the sperm whale (Physeter macrocephalus), the bottlenose dolphin (Tursiops truncatus) or the Risso’s dolphin among others.
In this case, we’ll focus on the risso’s dolphin or, as it’s also known, the Grampus griseus. It’s a quite big dolphin, between 3,5 and 4 metres long among the biggest registered specimens. Its round head (with no snout) together with the development of the melon (echolocation organ) are particularly striking.
No doubt, the most characteristic feature of this animal is the presence of marks all over the skin. This skin is very special, as it changes colour, from brown and grey when they are young to almost completely white when they become adults. These marks are, in many occasions, scars with a very diverse origin, generally caused by fights between specimens of the same species (territoriality), or between other dolphin species. They can also be feeding marks or marks caused by predators, parasites, genes, or skin disorders.
Feeding marks appear while foraging, cephalopod molluscs being their favourite (mainly squids and octopus they hunt in the depths). As many other odontocete cetaceans (group to which these cetaceans with teeth belong), they have very varied life strategies depending on food availability and, generally, it’s all about a group that involves the great divers.
The research about the Risso’s dolphin started in 2016 with the support by Fuerteventura council and the biosphere reserve of Fuerteventura. Moreover, it counts on the support by the Town hall of Pájara and the Environment Vice-Ministry of the Canary Islands Government. If you want to get a deeper knowledge about this research, don’t hesitate to visit the Facebook site: Risso’s dolphins in Fuerteventura.
Enjoy the Summer!