Shark Behavior 75
food, occasionally biting one another. Rays at Stingray City have more bite
marks on their bodies than rays that live in nearby areas where they aren’t
fed by tourists (see “Should people feed sharks?” in chapter 8).
Are any sharks territorial?
Territoriality usually means defending a locale against intruders; a dam-
selfish may defend its breeding and feeding territory against other fishes,
or a dog may defend its yard against other dogs or people. In this sense, we
have little evidence of territoriality in sharks. Some sharks react when other
sharks or people come too close, a behavior that could be called defense of
personal space. This defense was first described in Gray Reef Sharks.
Gray Reef Sharks have a distinctive, predictable reaction to being ap-
proached too closely, whether or not they are feeding. The approached
shark lifts its snout, arches its back, lowers its pectoral fins, and swims in
an exaggerated manner, swinging its head back and forth. If the intruder
doesn’t back off, the displaying shark may then attack. An unfortunate diver
was first to describe the sequence, after being bitten by a Gray while trying
to get close enough to take a good photo. This then led researchers to work
out the details by deliberately approaching sharks in very small submarines.
Sharks attacked the submarines also.
Something between such defense of personal space and possible ter-
ritoriality has been observed in the large resting aggregations of Scalloped
Exaggerated swimming display of
the Gray Reef Shark when its per-
sonal space is invaded by a diver,
another shark, or a small submarine.
Exaggerated body and fin positions
of an aggressive shark are shown on
left, with normal swimming postures
on the right. Redrawn by Chris Huh, Wiki-
media Commons, http://en.wikipedia.org/wiki/
File:Shark_threat_display.png, based on
R. H. Johnson and D. R. Nelson, Agonistic
display in the Gray Reef Shark, Carcharhinus
menisorrah, and its relationship to attacks on
man,” Copeia 1973 , 76 - 84 ; used with permis-
sion of the American Society of Ichthyologists
and Herpetologists