Key Takeaways

• A recent study of gray reef sharks found that "the same groupings of sharks — ranging from a couple up to as many as 20 — frequently returned to the same parts of the reef over and over again." The study was four years long, and some groups stayed together for the entire time of the study.
• G. A. Bradshaw, author of 'Carnivore Minds,' says, "Again, though, neuroscience tells us that sharks brains are not that different from our own – species differences are largely variations on a common theme. So when a marine biologist insists that the face of a pregnant fifty-year-old white shark named Deep Blue shows maternal glow, it is entirely consistent with what neuroscience predicts. White sharks feel love and emotions as much as we do."
• Although research has found that gray reef sharks are often in groups, and this may be to improve their ability to find prey, they do not hunt cooperatively. It appears that the group strategy is mainly used to find food, but the sharks kill and eat prey on their own, and do not tend to share. According to Yannis Papastamatiou, who runs the Predator Ecology and Conservation Lab at Florida International University, the shark's thinking may be something like, "If we hang out together and I see something, then you can come and try and take advantage of that," he says. "And alternatively, if you see something, then I can try and take advantage of that."
• Sea World reports that sharks can have a territorial drive, and that agonistic display, a specific swimming pattern, "usually precedes attacks out of territoriality." Several species of sharks have been observed making an agonistic display. These include gray reef sharks, blacktip sharks, and basking sharks.

Introduction

Social Relationships of Sharks

• A recent study of gray reef sharks found that "the same groupings of sharks — ranging from a couple up to as many as 20 — frequently returned to the same parts of the reef over and over again." The study was four years long, and some groups stayed together for the entire time of the study. Additional details from the study itself indicate that these social groupings primarily happen during the day, and they may be a way for sharks to find more hunting opportunities, by watching other sharks in the groups.
•  Blacknose sharks are another species that can form relationships. The groups are usually made up of sharks that are about the same size, and smaller Blacknoses are often bullied away. Of note, even though the sharks in a group are usually of similar size, there is still a hierarchy of eating where the largest in the group eats first.
• The following graphic shows the results of a study of two sand tiger sharks, in regard to their social interactions.

 

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• While most species of hammerheads are solitary, female scalloped hammerheads will sometimes be seen in large groups. It is believed that this is a means of protection from the males, who can be very aggressive toward solitary females.
• Another shark species that tends to be more solitary is white sharks. The exception to this is that couples can be formed and those sharks may stay together.

Comparison of Sharks and Dolphins

• According to American Oceans, dolphins are very social and they are in pods for all aspects of their lives, including traveling, hunting, and living. In comparison, while some sharks do show a preference for social connections, this is not true across all species, and often the groupings are formed only for specific activities.
• A 2017 article in Scientific American discusses research that shows "mammals, birds, fish, and reptiles (and now, it appears, invertebrates like bees and octopi) share common brain structures and processes that govern thinking and feeling." In other words, the minds of these animals can be explored using the same scientific model used for humans.
• G. A. Bradshaw wrote a book called 'Carnivore Minds,' and based on her research for the book, she says that great whites have amazing emotional sensitivity. She stated in an interview, "Again, though, neuroscience tells us that sharks brains are not that different from our own – species differences are largely variations on a common theme. So when a marine biologist insists that the face of a pregnant fifty-year-old white shark named Deep Blue shows maternal glow, it is entirely consistent with what neuroscience predicts. White sharks feel love and emotions as much as we do."
• "Dolphins have a brain to body ratio second only to humans." The image below is an MRI scan of a dolphin's brain and shows the many interconnected pathways.

 

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Hunting Behaviors

• A study from 2022 attempted to look at the hunting behaviors of white sharks. While only a limited number of sharks were studied, and it was only possible to form a hypothesis about the species' overall behavior, the researchers did find that in the sharks studied, many seemed to be part of a group when hunting, which they propose is so they can share information. The researchers also stated that there is likely a wide variety of behaviors within the species.
• Researchers in French Polynesia studied the hunting behaviors of sharks during some nighttime dives. They witnessed gray reef sharks following whitetip reef sharks. When the whitetips would try to capture prey within the reef, the gray sharks would attempt to catch the fish that escaped. There was no cooperation between the sharks, but the grays appeared to benefit from the practices of the whitetips. For the whitetips, there was no apparent benefit.
• According to Sharks-World, most sharks hunt alone when food is plentiful, but may cooperate with other sharks when food is scarce and there is a need to take down larger prey.
• Although research has found that gray reef sharks are often in groups, and this may be to improve their ability to find prey, they do not hunt cooperatively. It appears that the group strategy is mainly used to find food, but the sharks kill and eat prey on their own, and do not tend to share. According to Yannis Papastamatiou, who runs the Predator Ecology and Conservation Lab at Florida International University, the shark's thinking may be something like, "If we hang out together and I see something, then you can come and try and take advantage of that," he says. "And alternatively, if you see something, then I can try and take advantage of that."

Territorial Behaviors

•  Britannica reports that some sharks have shown territorial tendencies, while Blue Planet Aquarium reports that sharks are not generally territorial. This conflicting data led to a deeper dive on the subject.
• Territorial can be used in more than one way. In this article about species of sharks found in Hawaii, they discuss territorial in terms of where sharks choose to live. In this usage, stating that a shark is territorial simply means that they live in a well-defined area.
• In reference to that type of territorial, Robert Hueter, the director of the Center for Shark Research at Mote Marine Laboratory stated, "Sharks do not exhibit what animal behaviorists call true territorial behavior, which is occupying a specific area and defending that area. Sharks take their territory with them as they swim.”
• A second use of the term territorial in reference to sharks is related to the idea of a territorial drive. This is defined as, "the drive in animals and man to take, hold, and defend a particular area, zone, or turf." So since sharks generally don't have a set territory, territorial drive would relate to the defense of the territory they are currently in.
• Sea World reports that sharks can have a territorial drive, and that agonistic display, a specific swimming pattern, "usually precedes attacks out of territoriality." Several species of sharks have been observed making an agonistic display. These include gray reef sharks, blacktip sharks, and basking sharks.
• The following image shows several varieties of sharks, with many displaying agonistic behavior. The full reference for each image can be found in this research study.

 

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•  Bull sharks, which inspired the movie Jaws, display unpredictable territorial behavior.

Research Strategy