Natural History Notes
Grampus are found in herds of up to several hundred individuals and may be seen "porpoising" (leaping from the water) as they surface to breathe, and breaching. They sometimes ride the bow waves of a boat.
Grampus feed on fish and squid.
May Be Confused With
From a distance grampus are most easily confused with Atlantic bottlenosed dolphins. They may be most readily distinguished by the following differences:
| Grampus | Atlantic Bottlenosed Dolphin |
|---|---|
| SIZE | |
| To 13 feet (4 m). | Rarely to 12 feet (3.7 m);usually less than 10 feet(3.1 m). |
| BODY COLOR | |
| Young are uniform lightgray; older animals darkwith grayish regions onchest and belly; veryold animals white andscarred. | Dark gray on body; lightergray on sides; white or pinkon belly; may appear brownishin water. |
| DORSAL FIN | |
| To 15 inches (38.1 cm);sharply falcate; pointedon tip | To 12 inches (30.5 cm) lesssharply falcate; pointed ontip. |
| HEAD COLOR AND SHAPE | |
| Blunted and creased onfront; frequently allwhite in larger animals. | Uniformly brownish to graydistinctly bottlenosed. |
| MARKINGS | |
| Very often extensivelyscarred. | Less frequently scratchedand scarred. |
Distribution
Grampus are known to be distributed in temperate and tropical seas from at least eastern Newfoundland, south at least to St. Vincent, Lesser Antilles, and in the eastern and northern Gulf of Mexico. The species may not be as rare as the paucity of records suggests. Though they have been seen in Buzzards Bay on several occasions, grampus generally have an oceanic range and, along the Atlantic coast of North America, may be distributed from the Gulf Stream seaward, outside the theater of normal boating traffic.