American Oceans

What Do Sharks Eat?

Sharks are among the most prolific hunters in the seas. As one of the ocean’s apex predators, sharks eat a wide variety of food. All animal life in the oceans, from the smallest fish to enormous whales, have been prey to a shark. 

a great white shark eating a fish

But what do sharks eat in particular? Do they prefer fish over marine mammals? Let’s go through a shark’s diet and explain where they find the majority of their meals. 

The Shark Diet

Sharks come in various shapes and sizes, meaning that their prey will differ depending on the type of shark and where they live. Let’s go through the main sources of sustenance in a shark diet and what different species of sharks generally eat. 

Fish

Fish of all sizes can end up as prey to a shark—including other sharks! Fish, in general, are the most common prey for sharks. Whether they’re a spiny dogfish all the way to great whites, sharks love eating fish. Some common species of fish sharks hunt include:

  • Tuna
  • Salmon
  • Bass
  • Rays
  • Redfish

Sharks hunt fish by using sensory receptors located on their sides. These sense receptors are called lateral lines, and almost all fish have them. They help the shark’s nose and eyes find prey by allowing the shark to feel differences in pressure or disturbances in the water. 

Fish vary in their nutritional content. Some are high in fats, while others are lean. On average, an ounce of fish meat has between 40 and 80 calories, meaning a shark needs to eat a significant amount to sustain itself.

Seals and Sea Lions

Large sharks, like the great white, aren’t only predators to life in the seas but also to semi-aquatic marine life. Seals and sea lions spend a significant amount of time in the water, making them the perfect prey for large sharks. 

Great white sharks hunt seals and sea lions by thrusting themselves towards the surface and grabbing onto the animal with their powerful jaws. Sometimes great whites can explode out of the water, reaching up to 10 feet out of the water.

Since seals and sea lions are high in fat due to their blubber, they are an extremely nutritious meal for a large shark. One large seal or sea lion can sustain a shark for an entire week. An ounce of seal meat has approximately 30 calories, while sea lion meat is very similar. 

Mollusks

Mollusks are a large category of lifeforms that include squid and octopi, but also clams and oysters. Sharks that eat mollusks tend to be smaller. They prey on small, shelled animals that have no means of escape.

Larger sharks can eat larger mollusks, like octopus or squid. Hammerhead sharks, in particular, eat a lot of squid and octopus. Researchers have even found some sharks with squid beaks still in their stomachs! 

Sharks that hunt mollusks do it in various ways. When they’re shelled, sharks use special flat teeth to crush their prey. When they hunt non-shelled mollusks, sharks usually employ similar methods to their fish hunts. 

Mollusks are a wide category of life, so their nutritional value is variable. For example, octopus is high in protein but low in fat. It has approximately 20 calories per ounce. Shelled mollusks, like clams, have higher concentrations of fats and 25 calories per ounce. 

Crustaceans  

Sharks that eat crustaceans are bottom dwellers or sharks that live near the ocean floor. They live there because their prey, crabs, lobster, and other shellfish, live there too.

These sharks live at the bottom of the ocean, waiting to attack their prey. They have flat crushing teeth they use to crush and grind shells, making crustaceans a solid option for food. Crustaceans are high in protein, but low in fat and other nutrients. They have between 20 and 40 calories per ounce, depending on the species. 

Dolphins and Small Whales

Dolphins and small whales, such as pilot whales and the dwarf sperm whale, are often prey for large sharks, such as the great white and tiger shark. These sharks are large and powerful enough to outswim and overpower other large marine life.

When sharks hunt marine mammals, they look for the weakest members of a pod or group. These animals are usually slower and put up less of a fight. Marine mammals are also intelligent compared to other marine life, which means sharks have to use tactics much different from other animals. 

For instance, when great whites hunt dolphins, dolphins will fight back by ramming the shark with their tough noses. In response, great whites will separate one or two dolphins from the pod and attack them individually. 

Dolphins and whales, like semi-aquatic mammals, rely on blubber to keep them warm. That blubber is a nutritious meal for a shark. On average, dolphins have 22 calories per ounce of meat, and their flesh is high in fat and protein. 

Plankton

Only a few sharks feed on plankton, including the whale shark and the basking shark. By feeding on plankton, these sharks expend very little energy hunting. It’s a good thing too because plankton provides very little sustenance. 

Plankton-eating sharks feed by filtering massive quantities of water through their mouths. As they do so, the plankton separates from the water, providing them with a source of food. Plankton-eating sharks tend to be large, with the whale shark measuring in as the largest shark and fish in the ocean!

Plankton has almost no nutritional value on its own, which is why these types of sharks must eat so much. There are approximately 17 calories per ounce of plankton, although that can change depending on the type.

How Much Do Sharks Eat?

The amount of food a shark eats depends on its size more than anything. In general, sharks eat between 0.5 and 3 percent of their total body weight each time they hunt. For comparison, a person eats approximately 2 percent of their weight every day.

Sharks only hunt once every few days, though. Although their mouths are perfect for tearing up food, their stomachs aren’t the best at digesting it. That means they need a couple of days between meals to let the food digest. 

How Do Sharks Collect Food? 

Sharks collect food in two primary ways—filter-feeding or hunting. Filter feeding, as explained before, requires a shark with a specially designed mouth that filters plankton that they can eat.

Other sharks hunt their prey, which requires different methods depending on the animal they’re hunting. For example, shelled mollusks and crustaceans require a shark that hunts on the ocean floor, while seals and sea lions require a shark that can explode towards the surface to capture their food. 

Sharks that hunt fish look often for schools of fish. That way, they can capture more fish with less effort. Sharks that hunt dolphins or other marine mammals must outsmart their prey to capture it, so they employ multiple tactics. 

Final Thoughts

Sharks are the biggest hunters of the oceans, with only killer whales on par with their abilities. So, what do sharks eat in particular? A shark’s diet consists of a wide variety of animals, including fish, marine mammals, mollusks, and much more. Essentially, sharks eat anything they can get their teeth into!

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