Weddell Seal: Facts, Diet & Where to See Them

1. What Is a Weddell Seal?

The world's southernmost mammal

The Weddell seal is a "true seal", with no external ears and short front flippers. It lives around the entire Antarctic continent, mostly on the fast ice that stays attached to the coast. No other mammal breeds as far south.

It's named after James Weddell, a British sealing captain who sailed into the sea that also carries his name in the 1820s.

• Lifespan: usually around 20 years or more
• Conservation status: Least Concern
• Relatives: one of Antarctica's four "ice seals", with the crabeater, leopard and Ross seals

2. Size, Coat & How to Recognize One

Spotted, plump and permanently smiling

Weddell seals have a dark grey coat with silvery spots and streaks, which fades toward brown before the annual molt. Their heads look small for their big bodies, and the upturned mouth gives them a gentle, smiling expression.

Compared with a leopard seal, a Weddell is plumper, has a small, cat-like face, and lacks the leopard seal's long, reptilian head and huge jaw.

3. What Weddell Seals Eat

Fish from the deep

Weddell seals are fish specialists, which sets them apart from krill-eating neighbors like the crabeater seal.

• Antarctic silverfish: a small, abundant fish and a staple of the diet
• Antarctic toothfish: a large, deep-water fish taken on long dives
• Squid and other invertebrates: including some krill, but only a minor part of the diet

They often hunt by silhouette, swimming below prey and spotting fish outlined against the light coming through the ice above.

4. Record-Breaking Divers

Deep, long and carefully planned

Weddell seals are among the best divers of any seal. Most dives are shorter and shallower, but they're capable of going deeper than 600 m and staying under for more than an hour.

How do they do it? A few key adaptations:

• Oxygen storage: lots of blood rich in hemoglobin, and muscles packed with myoglobin to store oxygen
• Slowing down: their heart rate drops sharply on deep dives to save oxygen
• Collapsing lungs: they breathe out before diving, reducing problems with pressure

Research suggests they time their most extreme dives carefully, often when prey is deepest and the payoff is greatest.

5. Life Under the Ice

Breathing holes kept open by teeth

Unlike most seals, Weddells don't head north in winter. They stay in the far south under the fast ice, where the water is actually warmer than the air above.

To breathe, they use cracks and holes in the ice. When a hole starts freezing over, they keep it open by rasping at the edges with their teeth. It works, but it has a cost: their teeth wear down over the years, which may shorten their lives.

Weddell seals are also very vocal. Under the ice, they produce trills, chirps and whistles that can sound strangely electronic. On some Zodiac cruises, guides lower a hydrophone so you can listen in.

6. Pups & Population

Born on the ice, swimming within weeks

Weddell seal pups are born on the fast ice from about September to November, before most tourist voyages begin. Mothers nurse for around five to seven weeks, and pups start swimming within a couple of weeks of birth.

• Rich milk: pups can more than double their weight during nursing
• Underwater mating: males defend underwater territories below breathing holes
• Population: estimates vary widely, from several hundred thousand to around a million

Weddell seals are generally considered stable, and they were never heavily hunted on the scale of fur seals. The main long-term concerns are changes in sea ice and in the fish they depend on.

7. Where to See Weddell Seals

Beaches, floes and fast ice around the Peninsula

• The Antarctic Peninsula: often hauled out on beaches and ice at landings such as Neko Harbour and Paradise Harbour
• The South Shetland Islands: regularly seen on shore
• The Weddell Sea: on sea ice and floes, especially on eastern Peninsula itineraries
• The Ross Sea: large breeding groups on fast ice near McMurdo Sound, on specialist voyages

For all six of Antarctica's seal species and how to tell them apart, read our guide to seals in Antarctica.

8. Watching Seals Well

Sleepy does not mean tame

IAATO guidelines ask visitors to stay at least 5 m (15 ft) from seals, and farther if an animal reacts. Weddells are usually calm, but they're large, wild animals.

• Watch their reaction: if a seal lifts its head, rolls to face you or moves away, step back
• Never stand between a seal and the water: it's their escape route
• Crouch low for photos: eye-level shots of a resting Weddell are some of the best seal portraits. See our camera gear guide.
• Listen: if your guide has a hydrophone, ask to hear the seals under the water