GRAMPUS (T) 



Grampus griseus (G. Cuvier 1812) 



Other Common Names 



Risso's dolphin, gray grampus, white-headed grampus, 

 mottled grampus, Risso's porpoise, hard knocks (St. 

 Vincent), white blackfish (Cape Cod). 



Description 



Grampus reach a maximum length of about 13 feet (4 m). 

 The body is robust, particularly in front of the dorsal fin, and 

 lacks a distinct beak. The head is somewhat bulbous and is 

 marked on the front by a V-shaped crease with the point 

 downwards, which divides the melon into two parts. The 

 flippers are long and pointed on the tips. The dorsal fin, 

 located at about the midpoint of the body, is tall, to 15 inches 

 (38.1 cm) or more, and distinctly falcate. The body narrows 

 rapidly behind the dorsal fin and the tail stock is quite 

 narrow. The flukes are broad, concaved on the rear margin, 

 and deeply notched. 



The bodies of grampus are a uniform light gray at birth. 

 As the animals age, their color darkens to almost black with 

 distinctive regions of grayish white on the belly and chest. 

 The body of older adults is cream white or silver gray, 

 particularly on the head, with numerous scars, presumably 

 from encounters with other grampus and perhaps with the 

 squid, which are one of the species' major food items. 



The flippers, dorsal fin, and tail flukes usually remain 

 dark even in adults. 



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: 



Atlantic Bottlenosed 

 Grampus 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 light 

 g^ay; older animals dark 

 with grayish regions on chest 

 and belly; very old animals 

 white and scarred. 



Dark gray on body; lighter 

 gray on sides; white or pink 

 on belly; may appear brown- 

 ish in water. 



To 15 inches 

 sharply falcate; 

 tip. 



DORSAL FIN 



(38.1 cm); To 12 inches (30.5 cm); less 

 pointed on sharply falcate; pointed on 

 tip. 



HEAD COLOR AND SHAPE 



Blunted and creased on 

 front; frequently all white in 

 larger animals. 



Uniformly brownish to g^ay 

 distinctly bottlenosed. 



MARKINGS 



Very often extensively scar- 

 red. 



Less frequently scratched 

 and scarred. 



Figure 103.— Grampus are frequently found in small tight groups "porpoising." From a distance they may resemble the Atlantic bottlenosed dolphins, 

 though grampus have taller dorsal fins, blunted beakless heads, and lighter coloration. [Photo off Washington State by C. Fiscua.) 



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