Sharks The Animal Answer Guide

Shark Behavior 73

similar size and the same sex associating strongly, resulting in “long-term

preferred and avoided companions.” The strength of these associations was

comparable to the complex social structure of such highly social marine

mammals as dolphins and sea lions. Whether the sharks use the same visual

cues that we use to tell each other apart or some other cues remains to be

determined.

Do sharks fight?

Our knowledge of behavioral interactions in sharks has grown in recent

years with increased time and effort by researchers. We can generalize that

when two sharks meet around food, larger animals will generally domi-

nate smaller animals. Direct contact and fighting is rare; this makes sense,

given the damage that sharks can inflict on one another. Often, an interac-

tion ends when a smaller animal simply moves away as a larger animal ap-

proaches. Such size-determined outcomes have been observed in Smooth

Dogfish; Bull, Sandbar, Lemon, and Galapagos sharks (Carcharhinus gala-

pagensis); Bonnetheads; and White Sharks. In Bonnetheads, sex as well as

size determines behavioral interactions, with larger sharks and males domi-

nating smaller sharks and females. Juvenile Largetooth Sawfish (Pristis mi-

crodon) in captivity use their toothed rostrum (“saw”) in battles over food.

Using variation in fin coloration in Blacktip Reef Sharks to identify individuals. (Top panels) Left and right sides of a
single female (A) and male (B) shark. (C–H) Photos from left and right sides of the dorsal fins from six other known
sharks. (I–J) Photos of the same two individuals taken 10 years apart, showing that color patterns remain constant.
A–H, photos by Johann Mourier; I–J, photos by Ila Porcher and Johann Mourier; published in J. Mourier, J. Vercelloni, and S. Planes, “Evidence of social
communities in a spatially structured network of a free-ranging shark species,” Animal Behaviour 83 ( 2012 ): 389 e 401 ; used with permission