Coloration and Behavior of Common Dolphin — Murchison and Magnuson 517 
This swimming posture is maintained for 3-10 
sec and ends with a sudden return to the up- 
right swimming posture. 
Chafe. While swimming past an object, the 
fish brushes or rubs the lateral body surface 
against the object. If the chafe is directed 
against the tank’s standpipe or sides, the normal 
upright swimming posture is maintained, but if 
the object chafed against is above the dolphin, 
the chafe occurs in conjunction with a lean. 
Jerk. A single shudder or quiver passes over 
the body without visibly affecting locomotion. 
Defecation. A brownish-green cloud of fine 
material was ejected for a 1-3 sec period during 
typical swimming behavior. 
Surfing. The fish swims downwind just be- 
neath the surface, positioning itself in front of 
a wave crest. The anterior-posterior axis of the 
body is inclined from the horizontal at approxi- 
mately the same angle as the lead surface of the 
wave. With little or no caudal movement the 
fish travels rapidly forward in a horizontal 
plane at the same speed as the wave crest. 
The mouth closure, yawn, lean, and jerk of 
C. hip purus appear very similar to patterns ob- 
served in another pelagic fish, the Pacific bonito 
Sarda chiliensis (Cuvier) (Magnuson and Pres- 
cott, op. cit. ) . Other similarities are the tran- 
sient vertically barred coloration, shared also 
with the skipjack tuna, Katsuwonus pel amis 
(Linnaeus) (Nakamura, op. cit.), and con- 
tinuous swimming. These similarities in be- 
havior between a coryphaenid and a scombrid 
suggest that the functions may also be the same 
and are perhaps common to many pelagic pre- 
daceous fishes. 
