What Do Seals Eat?

Seals belong to a group of marine mammals called pinnipeds. There are over 30 different seal species, separated into three families. This group includes walruses, eared seals in the Otariidae family, and earless seals in the Phocidae family, which are considered true seals. In this article, we focus on the diets of true seals.

Just one look at a seal’s teeth provides a clue about its diet. Seals have sharp front teeth for grabbing and tearing and strong molars for crushing hard-shelled prey like crustaceans and marine mollusks. This is because seals are carnivores. Seals are also skilled, persistent hunters. Read on to learn more about seals’ diets and how they find food.

What Foods Do Seals Eat?

Seals are opportunistic carnivores and primarily eat fish because it is readily available. However, some species have unique dietary adaptations. For example, crabeater seals primarily eat krill, despite their name. Elephant seals generally eat fish, squid, and octopus. Northern elephant seals also consume rays and sharks. However, during the breeding and molting seasons, elephant seals do not eat and must rely on their fat reserves to sustain them. Leopard seals are apex predators, so in addition to fish, they also eat smaller pinnipeds, octopuses, and birds, particularly penguins. Also, ringed seals and Baikal seals eat zooplankton.

While seals’ diets vary by species, common prey includes:

• Fish
• Squid
• Octopus
• Mollusks
• Crustaceans, including krill
• Zooplankton

Seal diets also vary by location. For example, seals that live in the colder waters of the Arctic and Antarctic, like ringed seals and harp seals, eat more fish and crustaceans. However, seals that inhabit warmer waters, such as monk seals, have a wider variety of available prey, leading to a more diverse diet. Baikal seals are the only exclusively freshwater seal, so they eat a special type of zooplankton called Macrohectopus branickii and a fish species called golomyanka, both of which are only found in Lake Baikal in Russia.

How Do Seals Find Food?

Many seals range far and wide, diving deeply to forage for food or hunt for prey. Fortunately, seals have a layer of blubber to insulate them and provide energy when food is in short supply.

Foraging

The Weddell seal can dive to depths of over 2,900 feet and stay submerged for around 90 minutes. Harbor seals generally forage close to their haul-out areas, but they can forage for multiple days and travel over 30 miles in search of food when resources are scarce.

Northern elephant seals can dive to depths of over 5,000 feet and hold their breath for up to 90 minutes. They have several physical adaptations that allow them to conserve energy and oxygen while they’re diving. These seals have three times as much blood as a human. Plus, their blood contains more hemoglobin, which is the protein that carries oxygen.

Monk seals forage on the bottom of the sea and have been seen flipping over rocks to look for prey. They are also fast swimmers and pursue prey in open water.

Hunting

The leopard seal has a variety of hunting strategies. They flush fish from their hiding spots and stalk them. They also wait along the edges of the ice where penguins live. When the penguin jumps into the water, the seal ambushes it. The leopard seal uses suction to eat smaller fish and crustaceans. When it hunts for krill, the leopard seal uses filter feeding. Its back teeth come together in a way that lets it strain krill from the water. This is also true of the crabeater seal, which has specialized teeth that act like a strainer for krill.

Ribbon seals of the North Pacific Ocean have weaker fangs than some other seals, and they hunt their prey by piercing them with their teeth and swallowing them whole, as opposed to tearing the prey into pieces.

A study of harbor seals revealed they participate in cooperative hunting, as do leopard seals. Likewise, crabeater seals participate in cooperative foraging. Some seals also have different strategies depending on the time of day. The Baikal seal uses its eyes to search for fish during the day, while at night it uses touch to find crustaceans.