Depending on the species, sharks are known to both travel in groups and on their own. Some species display both social and solitary behavior. Many factors, such as time of year and prey availability, play an essential element in grouping behavior.
Requiem sharks – sharks of the family Carcharhinidae that are found in tropical and temperate waters – are often observed displaying solitary behavior. However, this is not conclusive. Evidence suggests in times of mating, certain species, such as white sharks, create bonds and travel with one another.
Another factor that influences the social structure of sharks is food availability. The ocean is a large open space, and food can sometimes be a rarity.
Time again, oceanic scavengers are gifted with a rare treat: the death of megafauna, such as whales. With such a sheer quantity of food on offer, individuals of the same species tolerate one another temporarily.
The same is seen in shark species in the deep sea. Typically, species such as the bluntnose sixgill shark will spend much of their time foraging the vast seascape in a solitary manner. In times of a rare “whale fall” group congregations will occur for the feast.
What sharks travel in groups?
Due to the complex nature of studying group interactions and behavior of sharks, data has been somewhat limited when it comes to understanding social structures.
However, studies have identified that many shark species exhibit companionships, hierarchical systems, and defined territories – an incredibly more complex system than scientists ever thought.
Such species that display group behavior include the hammerhead sharks. It is still unknown why these species gather in such great abundance, but some experts hypothesize that hammerheads undergo great migrations during the summer months to seek cooler water.
As with any animal that displays grouping behavior, there are tradeoffs.
While there are advantages to grouping, such as protection in greater numbers, there are also significant drawbacks. The larger the size of a school, the higher the competition is for feeding rights.
Hammerheads are not the only species to have been observed socially interacting with other individuals.
Blacknose sharks, a species of tropical requiem, have been studied in close detail. It has been concluded that individuals within the species can form relationships and bonds with other individuals of a similar size.
There is evidence of a hierarchical system, much like the pride of lions of the African savannah.
The largest individuals eat first until the rest of the group gets the leftovers.
This has also been recorded in bonnethead sharks, whereby it was observed that sharks actively assess the size of other individuals and alter their behavior correspondingly.
What sharks travel alone?
Many shark species spend a vast proportion of their lifespan on their own. One such example is the second largest fish in the world – the basking shark. This species spends much of its time foraging plankton in the sunlit waters. However, there have been records of congregations of over 100 members.
Even shark pups generally swim away from the mother as soon as they are born. No maternal post-natal care is given, aiding the solitary lifestyle.
Certain species, such as the tiger shark, are typically obligate loners. In other words, a shark that spends the vast majority of its lifecycle on its own. However, when environmental conditions are just right, it has been observed to see multiple tiger sharks sharing the same vicinity.
Port Jackson sharks are another solitary species. They often spend much of their time close to the seabed, foraging for crustaceans. However, even solitary species have been known to seek communication with peers.
A study by Pouca et al discovered this nonsocial species acquired information about feeding opportunities from individuals following trained counterparts. The study concluded that social living is not necessary for social learning.
Do sharks stay in one place?
Not all sharks stay in one place. Some travel great distances across the ocean and even freshwater systems.
In terms of movement patterns, shark behavior can be broken down into three subheadings: local sharks, coastal pelagic sharks, and highly pelagic sharks.
- Local sharks are species that stay in one place, typically slow-moving, bottom-dwelling species. They do not exceed an area covering 160km from a centralized point. Typical species that exhibit this localization include nurse sharks and wobbegong sharks.
- Coastal pelagic shark species migrate along shallower waters, often covering areas exceeding 1600km. They follow certain oceanic currents in search of food and mates. Such species include the Oceanic Blacktip and Tiger shark.
- The final category is the highly pelagic sharks. These are typically open water species that migrate vast distances, following oceanic currents and borders searching for food. These are generally fast and streamlined species, including the Blue shark and Mako shark.
To conclude, many shark species are solitary species. However, group activity may occur within shark species due to specific environmental conditions and seasonal influences. It is thought that socially active sharks have an increased survival rate compared to their solitary counterparts.