Sharks have been evolving for millions of years and, in that time, have perfected the art of predation.
However, there are hundreds of different species of shark, each of which has its own hunting techniques and strategies.
Some sharks, like the whale shark, eat tiny organisms known as plankton, which requires a very different hunting technique to that employed by fast-swimming predatory sharks like the mako or great white.
Despite that, they still rely on the same senses to locate their prey and maximize their chances of a decent meal.
What is Considered a Shark’s Prey?
What do sharks eat? Some shark species target marine mammals, like seals and dolphins, while others prefer more bite-sized offerings like small crustaceans, shrimp, and plankton.
There’s even one shark that adopts a flexitarian approach to survival. The bonnethead shark is the only species known to have the ability to break down cellulose, which means it can eat seagrass as well as shrimp, fish, and crabs.
Other species of hammerhead have perfected the art of hunting stingrays but also have an appetite for squid.
All large predatory sharks, including the shortfin mako and the bull shark, feed mainly on bony fish like tuna and mackerel but will also prey on turtles, mammals, and other sharks.
Bottom-dwelling sharks like the wobbegong also eat fish but use a different technique for catching them. They’ll also feed on lobsters, crabs, and octopuses.
Some sharks are highly selective about their diets, while others will sample almost anything. The tiger shark “is notable for having the widest food spectrum of all sharks.” Its diet includes:
- Birds
- Crustaceans
- Dolphin
- Fish
- Squid
- Sea snakes
- Turtles
Tiger sharks are so unselective about what they eat that they’ll consume all sorts of strange, non-edible items, from chicken coops to a whole suit of armor!
How do Sharks Find their Prey?
Sharks have three highly developed senses that enable them to pinpoint their next victim’s whereabouts.
Sense of Smell
All sharks have an acute sense of smell that enables them to detect scent molecules dispersed in the water.
Research shows that lemon sharks can detect “as little as 1 part of tuna extract in 25 million parts of seawater.” In other words, they could smell ten drops of extract in an average-sized swimming pool.
Blacktip and gray reef sharks are even more advanced, detecting one drop of grouper fish extract in a quarter-acre lagoon.
Studies also suggest that, although the shark’s “olfactory systems are similar across different species,” some have adaptations that may enhance their sense of smell even further.
Bonnethead sharks lack the olfactory knobs found in other non-hammerhead species but have “larger lamellae in areas where the water flow over the olfactory bulb is highest.”
This feature enables the bonnethead to “detect dilute scents carried in fast-flowing water.”
Even the whale shark uses its sense of smell to locate its prey, honing in on the most protein-rich waters where the concentration of plankton is greatest.
Not only do sharks have a highly developed sense of smell, but they also smell in stereo. This ability means they can pinpoint their prey’s location more accurately.
If the left nostril picks up a smell before the right, the shark knows its prey is to the left and heads in that direction.
Researchers also suspect that hammerheads might be even more effective at locating their prey by smell because the space between their nostrils, or nares, is much greater than in other species.
Lateral Lines
All sharks have a lateral line system that “contributes to prey tracking, prey localization, and capture precision.”
They have one lateral line on each side of their bodies, extending from the snout to the tail. This sensory organ consists of a hollow tube filled with pores, sensory cells, and “fluid-filled subepidermal canals.”
Together, these respond to hydrodynamic stimuli, such as vibration, water movement, current speed, and direction.
The lateral line also forms part of the shark’s olfactory system, picking up on “smell plumes” that its nostrils can’t detect.
Sharks also use their lateral line to navigate, using the information it gathers about currents and the earth’s magnetic field to give them a sense of location and direction.
Ampullae of Lorenzini
Within the shark’s snout lies a complex network of electroreceptors that complements the olfactory and lateral line systems, enhancing its ability to track and locate its prey.
The ampullae of Lorenzini is a network of jelly-filled pores that respond to electrical stimuli.
It can detect the weak electrical signals generated by the muscle contractions of fish and other prey species, enabling sharks to locate hidden prey and hunt effectively in murky waters and low light conditions.
The ampullae of Lorenzini are so sensitive they can detect a heart beating, which has led some to theorize that a shark “can sense fear by detecting electrical impulses given off by a diver’s accelerated heartbeat.”
How Do Sharks Hunt?
Sharks employ a wide range of hunting strategies to secure their prey.
Some use stealth and ambush to surprise their victims, while others form packs to take on larger prey species or herd schools of fish into submission.
Many shark species stalk their prey before they attack, conserving their energy for the moment their victim is at its most vulnerable. They’ll also target weak or injured individuals to make the hunt easier.
How do Sharks Attack?
Some sharks are endothermic, generating their own body heat and warming their muscles to the point that they can engage in high-speed chases, regardless of the temperature of the surrounding water.
Shortfin makos are the fastest sharks in the ocean, reaching speeds of well over 50 kph. Researchers believe they rely less on electroreception and more on smell, hearing, and vision.
Once a mako shark has identified its victim, it lies in wait in shallow bays and inlets before ambushing its victim at high speed.
Other shark species have developed their own signature moves and hunting styles. For example, the bull shark bumps its prey repeatedly before attacking it.
Researchers believe this approach is used to either weaken the victim or assess its size and strength. It then circles its prey, biting and bumping it repeatedly until it’s too weak to flee.
Great whites are more clinical in their attacks and attempt to either incapacitate or kill with a single strike.
Like the mako shark, a great white lies in wait, using deeper water as its cover before exploding vertically toward its prey.
Hammerheads have developed a unique hunting technique that involves pinning their prey to the sea floor before taking bites out of its fins. They have perfected this approach to capture stingrays in particular.
Another shark species with a unique form of attack is the thresher shark.
By flinging its long caudal fin over its hit, the thresher shark creates a shockwave that stuns the fish, enabling it to swim back and scoop up the disoriented remains.
Do Sharks Circle their Prey?
Many species of shark will circle their prey before they attack, not because they’re trying to intimidate them, but because they’re trying to get a better idea of the size and nature of their target before they attack.
Researchers at the University of Tokyo also believe sharks circle to “draw a map of their surroundings.”
By swimming in circles sharks and other marine creatures can “scan the sea around them and determine the maximum and minimum strength of surrounding magnetic field lines.”
This gives them a clearer idea of their own position and that of their prey.
Circling a victim also gives the shark a 360° view of what it’s about to attack, increasing the chances of a successful strike.
Not all sharks circle before they attack, with many bottom-dwelling species relying on stealth and ambush to secure their prey.
Why Do Sharks Hunt for Other Fish?
Sharks are a type of fish, so the fact that they primarily hunt fish makes them almost cannibalistic. Some sharks will even prey on other shark species or target members of their own.
This behavior is typical of an opportunistic predator – it eats whatever is most abundant.
As there are a lot of fish in the sea, most sharks will take advantage and make fish the mainstay of their diet.
Some larger predatory species, like the great white, prefer marine mammals but still eat fish if that’s the only available resource.
Do Sharks Hunt in Packs?
Some sharks are predominantly solitary, only coming into contact with others during mating season.
Others form packs to increase their chances of success when hunting.
Blacktip reef sharks often hunt together, working collectively to herd schooling fish into shore where they’re easier to catch.
A study of reef sharks on the French Polynesian reserve of Fakarava Atoll revealed two species hunting together.
Researchers observed grey reef sharks following foraging whitetips “to increase its predatory success rate.”
As the slimmer, more agile whitetip reef sharks flush out fish hiding in the reef, grey reef sharks come in and steal the victim from under their noses.
By exploiting the assets of the whitetip, grey sharks can increase their “predation success by almost 25 percent.”
Although sharks hunt in groups, they don’t tend to form cooperative packs like orcas and dolphins. It’s more of an opportunistic relationship in which “the first shark to catch the fish gets to eat it.”
Even great whites, which were long thought to be solitary hunters, prefer to hunt within “eavesdropping” distance of other great whites.
That way, they’re close enough to detect a successful kill and potentially steal some of the remains.
Other shark species, like blacktip reef sharks and sevengill sharks, show some signs of cooperation, with sevengill sharks working together to capture larger prey species like seals.
Groups of blacktip sharks have been filmed herding schooling fish into tight groups or chasing them into shore to increase their chance of a successful kill.
Do Sharks Hunt at Night?
Most shark species are more active at night and specifically at dusk and dawn, although some feed throughout the 24 hours.
Researchers have also found that sharks will adjust their feeding times to avoid potential predation by larger shark species.
A study of several shark species in the Gulf of Mexico revealed that the largest species, namely tiger sharks, fed whenever they liked and “tended to hunt during the middle part of the day.”
On the other hand, bull sharks preferred the early mornings, while sandbar sharks hunted primarily in the afternoons and blacktips in the evenings.
What do Sharks Hunt the Most?
More than anything other species, sharks hunt for fish, probably because fish are so abundant in the oceans.
Some sharks, like the bonnethead, prefer crustaceans to fish but will vary their diet if required.
Others, like the great white, target high-calorie pinnipeds like seals and sea lions but will also eat bony fish like tuna and mackerel if options are limited.
Conclusion
Sharks are highly evolved predators with acute senses that can accurately detect and locate potential prey in the vast ocean.
They are highly adaptable and opportunistic, eating whatever’s most abundant.
Some sharks are more solitary than others, but many use proximity to other sharks to increase their own chances of success.
Some may even cooperate to bring down larger prey species or target a large school of fish.
Sharks’ hunting strategies are widely varied but hugely successful, making them some of the most efficient predators on earth.
Nicky is a British adventurer and animal lover who spends her time exploring the natural world and writing about her experiences. Whether on horseback, underwater, running, hiking or just standing with a fishing rod in hand, she embraces everything her adopted home of South Africa has to offer.