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Are sharks territorial?

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A school of scalloped hammerhead sharks, which gather in the thousands to reproduce.
A school of scalloped hammerhead sharks, which gather in the thousands to reproduce.

By Blaise Jones

Many movies featuring sharks often have them patrolling a set area as their home territory. This was the crux of the movie “Jaws” – the shark established a territory off of the beach and would not leave. However, as usual, Hollywood’s depiction of shark behavior is less than accurate.

Don’t tarry in the territory
What exactly does being territorial mean? According to the Encyclopedia Britannica, territorial behavior is defined as, “the methods by which an animal, or group of animals, protects its territory from incursions by others of its species.” A territory is an area an organism claims as its own for the purpose of mating, nesting, roosting, or feeding.

A horn shark.
A horn shark.

Broadly speaking, this definition does not match the behavior of most sharks. The majority of shark species are migratory and do not spend much time in a single area. They mostly follow sources of food, like schools of fish, or are following a migration instinct. However, as is common when discussing ecological concepts in regards to all shark species, there are exceptions to the rule.

Dangerous Dancing Sharks
Certain species of shark do display a form of traditional territorial behavior. Species that have been observed guarding set territories are the horn shark, blacktip reef shark, nurse shark, Caribbean shark, bull shark, sandbar shark, and gray reef shark.

The Gray reef shark is well known for its territorial behaviors. Research shows that they rarely leave their territory, which can stretch for as far as 20 square miles (53 km2), and even when they leave, they usually return. These territories often revolve around a set landmark, such as a sandbar or stack of coral.

Gray reef shark.
Gray reef shark.

Gray reef sharks were also the first shark to be observed doing the now widely known threat display. The display includes an arched back, gaping mouth, and erratic figure-eight swimming pattern. The first known observation of this behavior came from a scuba diver who was attacked after he entered the displaying shark’s territory.

Moriah Moore, a marine biologist with the Coastal Marine Education and Research Academy, recounts a time where she experienced shark territorial behavior first hand while working as a diver at an aquarium:

“I was scrubbing our fake coral to get the algae off of it when something hit me extremely hard in the shin. It was like getting hit with a baseball bat! It happened so quickly that I didn’t immediately see what had hit me. Then I saw a 4-foot sandbar shark coming at me fast! That was when I learned that sandbar sharks are very territorial and I was the unfortunate sucker cleaning her part of the tank.”

Moore then goes on to describe how each time the shark charged her, it did not bite her or ram her with its snout. Instead, “she would have a sudden burst of speed and would hit my shin right at the base of the front of her dorsal fin.”

While it cannot be said for all shark species, it seems at least with the sandbar shark that there is a distinct difference between territorial attack and hunting attacks.

Personal Shark Space
However, most sharks do not have large areas they deem their territory. Most sharks instead have a more confined territory, described as their “traveling territory”. While species like the gray reef shark will begin displaying as soon an interloper enters a certain area, most sharks will ignore potential intruders until they approach within a certain distance of the animal.

This personal bubble behavior is prominently displayed by scalloped hammerhead sharks during their large mating gatherings. During these events, the scalloped hammerheads gather in huge schools several thousand strong. Each shark maintains an equal distance from their neighbors as they swim in the school, which can be theorized as the extent of their personal bubbles. The larger females gather at the center of the school, which is considered the best location to attract a mate, and will defend their position from any other females that enter their traveling territory.

Fierce Food Fights
Another type of territorial behavior certain species of shark display is “food territory.” This behavior has been observed prominently in the great white shark. After making a kill, the shark will essentially cordon off an area around its kill that it will vigorously defend from any and all intruders.

In the cases of several white sharks coming across an already dead animal, the larger individuals will quickly set up a hierarchy of feeding, much like what has been observed in pack animals. The larger females feed first and the younger individuals remain on the outskirts on the kill until the older females are done feeding.

So, while not all sharks have a traditional territory, most do have a flexible and changing sense of personal space. So, if you’re ever in the water with a shark, give it some room. The last thing you want is to annoy a shark.

Watch the aggressive behavior of a gray reef shark below:

Sources

  1. https://www.britannica.com/topic/territorial-behaviour
  2. http://www.smithsonianmag.com/science/qa-diving-deep-killer-shark-science-shallows-180959530/?no-ist
  3. Sharks: The Animal Answer Guide by Gene Helfman and George H. Burgess
  4. The Encyclopedia of Sharks by Steve Parker
  5. The Secret Life of Sharks by Dr. A. Peter Klimley
  6. Moriah Moore, Marine Biologist with the Coastal Marine Education and Research Academy
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