Shark Attack — Fellows and Murchison 
to be a critical distance. (3) Headswinging be- 
havior immediately preceded attack behavior. 
(4) Headswinging behavior appeared only 
when the diver was behind the shark. 
The same exaggerated swimming motion has 
been reported by Hobson (1961:29) as occur- 
ring in at least two species of Carcharhinus. 
In one case the behavior immediately prefaced 
an attack on a diver at Wake Island. The present 
authors agree with Hobson’s opinion that the 
behavior permits the maintaining of visual con- 
tact with an object directly behind the shark, 
but they also suggest that the behavior might 
151 
signal an intention of attack on the part of a 
harassed shark. 
It is the opinion of the authors that the inci- 
dent reported here was a defensive behavior 
by the shark, provoked by pursuit in a confined 
area. 
REFERENCES 
Hobson, E. S. 1961. Sharks increasing visual 
field. Underwater Naturalist 2:29- 
F. Mautin, and E. S. Reese. 1961. 
Two shark incidents at Eniwetok Atoll, 
Marshall Islands. Pacific Sci. 15:605-609. 
