There isn’t much or reliable information about the social structures of sharks, given the complexity of studying their individual interactions and behavior. However, in recent years the relationships between fish once considered simple and socially primitive have been better understood.

Thus, there is evidence that some shark species manifest a diverse social structure. The traditional image of a solitary shark tends to be half true because not everyone prefers to swim, hunt and feed without any company, on the contrary: they can be territorial and establish hierarchical positions, more often around the feeding areas.

Regarding the above, many have the need to cooperate and share several activities so that from time to time they show some sociability and form large groups, made up of about 100 or more members. This kind of association is the case of hammerhead sharks (Sphyrnidae), accustomed to gather in vast numbers around areas with abundant food.

There is evidence that some shark species manifest a diverse social structure.

The information available on social structure is equivalent to knowing the habits of segregation of some species, not about all of them since it is impossible to generalize but it is possible to formulate hypotheses based on such observations. The following are examples of social behaviors discovered, which are far from the supposed brief and simple relationships between sharks:

Most white sharks (Carcharodon carcharias) are solitary, but couples sometimes swim together for a long time. Apparently, the link does not break immediately after mating. Females are at a higher hierarchical level than males, but body size is a major factor in determining who dominates whom.

They are perhaps the shark species that shows the most complex social structure. Each year couples or small groups of individuals meet whose members are almost always the same age, the same size, and the same gender.

When conflicts arise within a group, members resolve the situation through rituals and demonstrations of power; There are rarely strong physical attacks.

Blacknose sharks (Carcharhinus acronotus) can establish and maintain relationships. They form groups but are very selective, so they tend to build links only with individuals of the same size. Also, they have the habit of harassing or scare smaller Blacknose sharks. The rules within a group are usually clear. The big sharks eat before the smaller ones, which wait until they finish up under penalty of being involved in the frenzy of the moment and also become the food of its companions.

The Scalloped Hammerhead (Sphyrna lewini) usually do not gather with other animals of the same species.

The Gray reef sharks (Carcharhinus amblyrhynchos) only meet with female gray reef sharks when they have to mate.

The sand tiger sharks (Carcharias taurus) congregate in groups of 5 or 6 individuals off the Atlantic coast of the United States and stay stacked on top of each other until it is their turn to mate.

Socially active sharks have higher survival rates than solitary sharks, but it is not known with certainty why some species form groups, the factors that affect the constituents, the mechanisms of recognition among their members, the types of interactions within them nor the effects they have on their organization, structure and complexity.

Of course, these issues provide a perspective on future research, and a broader picture is expected to highlight the importance of sharks in shaping ecosystems and oceanic food chains.

Sharks don’t have to rely on each other to survive.

SOCIAL STRUCTURE OF SHARKS

Survival of the fittest is the best way to describe the social relationship of sharks.

Sharks don’t live in groups but tend to live on their own. Even the offspring have to take care of themselves from the very minute that they are born. Since they don’t spend much time together, they do not have a social hierarchy.

SHARKS ARE LONERS

Sharks don’t have to rely on each other to survive. However, some species of sharks cooperate when hunting. They can take down larger prey this way. They will hunt alone though as long as there are adequate food supplies available.

Many experts believe that this individuality has helped sharks to survive for millions of years.

Sources:

https://seaworld.org/en/animal-info/animal-infobooks/sharks-and-rays/behavior

Jeffrey C. Carrier, John A. Musick, Michael R. Heithaus. Biology of Sharks and Their Relatives, Second Edition. 2012

http://voices.nationalgeographic.com/2013/03/11/shark-have-social-networks-learn-from-friends/

http://animaldiversity.org/search/?q=shark&feature=INFORMATION

BioExpedition Publishing © 2017.

Most sharks make most of their activities during the afternoons and prefer to hunt at night. They are usually solitary: they swim and hunt alone most of the time, but they meet with other sharks in some special cases, like the period of mating or the zones abundant in food.

Some species show a social structure based on groups called “schools” without a strong reason for this because sharks do not need special protection against predators. The sharks that socialize usually segregate according to the size of the individuals.

Some species show a social structure based on groups called “schools”.

Hammerhead sharks are an obvious example of social sharks with a clear hierarchy, and it is common to find them gathered around islands and other areas with an abundant food source. Other species try to be careful with them, as their excellent maneuverability given by the shape of their heads is advantageous compared to other sharks.

However, some species hunt in groups when it comes to obtaining a large prey. Sharks form large groups, and all cooperate first by surrounding the prey, and then, when they are already captive, they gradually approach it until one of the predators takes the first bite. It is then that the others begin to attack and end with the prey. This cooperative behavior is extremely rare.

The methods of hunting in this predators are different and make the element of surprise their primary weapon. Benthic sharks, for example, camouflage themselves beneath the bottom of the ocean and if they detect a possible prey, they stay still, waiting for the animal to get close enough to attack it from below and occasionally, to swallow it whole.

In contrast, pelagic predators must cautiously approach the prey and hurl themselves at it before it knows what is happening. Sometimes, before eating, they perform an entire display of exaggerated movements that they intend to threaten. If it is a large animal, sharks wait for it to bleed to death and then eat it.

Hunting activities require a lot of energy, and as a consequence, large predatory sharks feed only a few times a week and are not always eating, as is often believed. Small species, on the other hand, eat a couple of occasions during the day since their prey are also small.

Their feeding behavior changes according to the presence of prey and the competition for them. If sharks stimulation is intense, it is possible that the excitement increases and they are victims of a frenzy that results in cannibalism.

Migration is a fundamental activity for some sharks, whose motive is the search for food as their prey also migrate and to reach the areas where they mate and spawn. Their journeys can take them through all the ocean basins traveling thousands of kilometers during a year. Sharks remember the migration patterns of their favorite prey and do not hesitate to follow them, but their migratory patterns become more complex than those of birds.

Sharks remember the migration patterns of their favorite prey.

Occasionally they congregate around fishing boats because they remember that the fishermen throw discarded animals.

Several species can travel at the same time, and until recently, some thought that most stayed in one place, but that is not accurate. For example, blue sharks (Prionace glauca) can migrate from the United States to Brazil, which is a significant distance. Another famous migrant is the whale shark (Rhincodon typus), which goes to specific areas to spawn in corals.

It is worth remembering that not all sharks are aggressive and they do not attack for pleasure. Many species are characterized by their docility and even by their timidity. As an example, the shark whale mentioned above is very peaceful, quiet and does not react with fear or aggression to the proximity of humans.

Sources:

https://en.wikipedia.org/wiki/Shark#Behavior

http://www.defenders.org/sharks/basic-facts

https://seaworld.org/en/animal-info/animal-infobooks/sharks-and-rays/behavior

http://animaldiversity.org/search/?q=shark&feature=INFORMATION

http://www.arkive.org/

BioExpedition Publishing © 2017.