Many people love seals and sea lions, and it's easy to see why: they’re playful, adorable, and quite photogenic. But what is the difference between seals and their cousins the sea lions? Both have fins for feet, making them pinnipeds. But the sea lions' have long fins covered with skin, while seals swim with short and stubby fins. Also, sea lions have small flaps covering their outer ears—seals do not. Try to spot these differences as you flip through the slideshow!
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Seal and Sea Lion Pictures
Seal or Sea Lion?
Credit: Flickr User wildestanimalSeals and sea lions have many similarities, and are in the same family of Pinnipeds, but they lead very different lives. Seals are smaller than sea lions; male Stellar sea lions can grow to be up to 2,200 pounds. Seals also are suited to spend more time in the water than sea lions, which can "walk" on shore with their large flippers and spend time in large social groups. Another give-away is that sea lions have external ear flaps, whereas seals don't have external ears—if you look closely you can see tiny ear holes.
These two are sea lions. (See the ear flaps?)
Grey Seal Strikes a Pose
Credit: Brian Skerry, National GeographicA Grey Seal (Halichoerus grypus) poses in the waters off Acadia National Park in Maine. Grey seals live on both coasts of the Northern Atlantic, with breeding colonies in Great Britain, Ireland, and down the eastern coast of North America from Canada down to New Jersey.
They used to be hunted in the United States, but their numbers have grown since the passing of the US Marine Mammal Protection Act in 1972.
Learn more about National Geographic photographer Brian Skerry, who took this photo, and see more of his photos.
The Endangered Hawaiian Monk Seal
Credit: Caleb Slemmons, Flickr name TurasPhotoScientists from the U.S. and Greece are working from opposite sides of the ocean to save the Hawaiian (pictured here) and Mediterranean monk seals. The IUCN Red List of Threatened Species has declared both species to be critically endangered. Their relative, the Caribbean monk seal, has already gone extinct.
A study conducted in 2010 led researchers to conclude that one-fifth of the world's vertebrates are threatened wtih extinction. Meet some of the marine vertebrate species that are among the threatened in the Backbone of Biodiversity of Risk image gallery.
A Mediterranean Monk Seal Pup
Credit: MOm/ A.A. KaramanlidisWatch a recorded webcast about the latest efforts in Greece to study and save the critically endangered Mediterranean monk seal. Centuries of human exploitation and habitat destruction have caused the remaining populations of Mediterranean monk seals (Monachus monachus) and Hawaiian monk seals (Monachus schauinslandi) to drop to perilously low numbers, while the Caribbean monk seal (Monachus tropicalis) has become extinct.
Southern Elephant Seal, Gold Harbour, South Georgia
Credit: Justin Hofman/Nature's Best PhotographyThe largest of all seal species, the southern elephant seal (Mirounga leonina) is found in chilly Antarctic and Subantarctic waters. The male seals dive as deep as 1,430 meters (over 4,600 feet) and stay at depth for up to two hours.
“The southern elephant seal is a truly restrained behemoth. Males can grow to be five times larger than females, up to 5,000 pounds. This elephant seal may look fierce, but he was simply yawning over and over in the wave-wash. This allowed me to try multiple ways of getting this impressive pose, including lying down in the water without disturbing him.” -- Nature's Best Photographer, Justin Hofman
Harp Seal Pup at Sunset
Credit: Brian Skerry, National GeographicA harp seal (Phoca groenlandica) pup rests on the ice at sunset in the Gulf of St. Lawrence, Canada while its mother hunts. Adult harp seals have dappled gray fur, but the babies are born white and are known as "whitecoats." After 12 days of nursing, grey color begins to show and, a week later, the white fur begins to fall out in patches.
Elephant Seals Tussle for Territory
Credit: Robert Schwemmer, CINMS, NOAAMale northern elephant seals face off on the beach by vocalizing through their extended noses, called proboscises. Every winter, when the seals return to the beach where they were born to breed, males arrive first to tussle for territory. The winners of these fights are the "alpha" males, and they get the biggest and best territories. After the beachfront property is divvied among the alpha males, the females arrive for breeding. Learn about how scientists track elephant seals with satellite tags at the Census of Marine Life.
Galapagos Sea Lion Yawning
Credit: Rod Mast/Marine PhotobankA Galapagos sea lion (Zalophus wollebaeki) rests on a beach in Ecuador. The population of these charming animals swings wildly during El Niño events, but is declining overall. They are currently listed as endangered on the IUCN Red List. See more pictures of animals at risk.
Crabeater Seal
Credit: Copyright Brian Skerry/National Geographic MagazineThe crabeater seal (Lobodon carcinophaga) is found on the ice of Antarctica, but surprisingly they don't eat crabs! The seals primarily eat krill, tiny crustaceans that play a large part in the Antarctic ecosystem.
Harp Seal, Prince Edward Island National Park, Canada
Credit: John Sylvester/Nature's Best PhotographyHarp seals are protected in the United States by the Marine Mammal Protection Act. Although they are not considered endangered, as sea ice melting earlier and earlier each year, available harp seal breeding grounds are being lost in the North Atlantic and Arctic.
“Every March, up to 200,000 harp seal pups are born on sea ice in the Gulf of St. Lawrence. In 2011, storms and lack of ice-cover due to a warmer winter climate resulted in hundreds of seal pups being washed up on the shore of Prince Edward Island. Like many, this young seal faced an uncertain future. Nearly three weeks old, it was weaned but not yet ready to swim on its own, leaving it vulnerable to predation or drowning. For me, this image expresses the vulnerability of not only this individual, but the entire harp seal population.” -- Nature's Best Photographer, John Sylvester
Hawaiian Monk Seal
Credit: James WattThe critically endangered Hawaiian monk seal (Monachus schauinslandi) is one of hundreds of marine species that can be found cruising the waters of Papahānaumokuākea, a chain of islands northwest of the main Hawaiian archipelago. Despite living in protected habitat, Hawaiian monk seals frequently become entangled in fishermen's nets, threatening their survival. It's estimated that only around 1,200 individuals survive today. Watch a recorded webcast about the latest efforts in Greece to study and save the critically endangered Mediterranean monk seal.
Elephant Seals Laze on the Beach
Credit: Su Yin Khoo (Flickr user kyusin)These southern elephant seals (Mirounga leonina) may look like beach bums, but when they are in the water hunting, they are anything but. Satellite tracking by tagging the animals has found that, during the 10 months they spend at sea, elephant seals spend most of their time underwater, hunting fish and squid at depths of 1,300 to 3,300 feet (400 to 1,000 meters).
In the deep water, it is very dark, and elephant seals don't have a great sense of smell, like penguins, or the ability to echolocate, like whales, to help them hunt. They can't even see particularly well in daylight -- but in the dark it's a different story. Elephant seals' eyes are specialized for dim light and, in particular, to light at the wavelength of 485 nm -- which is the same wavelength given off by the bioluminescent lanternfish that are the seals' main prey. And the seals preferentially spend more time foraging at the depth where most bioluminescent animals live.