|Population||Unknown (2008 est.)|
|Conservation status||Least concern|
The grampus or Risso's dolphin (Grampus griseus) is a species of dolphin of the family Delphinidae, and found in cold to warm waters worldwide.
The word "grampus" may have had its origins with the Latin crassus piscis, meaning "fat fish". This in turn led to the Old French word graspois, and hence to Middle French graundepose (the French pois is based on the Latin pisce, i.e. "fish"), both words meaning "grand fish". The name has also historically been used for the pilot whale (Globicephala melas) and the orca (Orcinus orca). Its other common name honors Antoine Risso (1777-1845), a Niçard naturalist who provided the first description of the animal to Western science.
The grampus is large, from an average of 10 feet up to 13.1 feet in length, and weighs 660 to 1,100 pounds. females are slightly smaller than males. The most striking feature is the unusual head profile: the grampus has a voluminous, almost vertically sloping forehead with a distinctive melon, and has a wide, but very short snout. Another characteristic is the sickle-shaped, tall dorsal fin, which is similar to that of a young killer whale. The pectoral fins are also very long and narrow, but only very slightly curved. The tail fluke is wide with a deep indentation in the middle.
The grampus is very variable in color. Calves are still silver-gray, then become darker and, as older young animals, are almost black with a few white spots on the belly. Then the colors fade back to a slate gray. The colors stay strong longer on some parts of the body than on others. The resulting pattern is individually different. In addition, there are numerous scars in older animals, which result from both intra-species fights and from fights with other animals, such as cephalopods or sharks, and are more common in males than in females.