The 20 Biggest Mammals

The phlegmatic capybara, the world's biggest rodent. Wikimedia Commons

Sure, everyone knows that whales are really big, and a hippopotamus is roughly the same size as a rhinoceros—but do you know what all of the biggest mammals are, by category? Below, you'll find a list of the 20 biggest mammals alive today, in 20 different weight classes, starting with the most humongous of the bunch (the Blue Whale) and working our way down. (See also The 20 Biggest Prehistoric Mammals.)

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Biggest Whale - The Blue Whale (200 Tons)

blue whale
The Blue Whale, the world's biggest whale. Wikimedia Commons

At about 100 feet long and 200 tons, not only is the Blue Whale the biggest mammal in the world today, but it's the largest vertebrate animal in the history of life on earth: not even the largest dinosaurs approached it in bulk. (Sure, some titanosaurs were over 100 feet long, but they almost certainly didn't weigh more than 100 tons.) Fittingly enough, the Blue Whale is also the loudest animal on the planet; this cetacean can vocalize at 180 decibels, enough to render most other animals deaf.

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Biggest Elephant - The African Elephant (7 Tons)

african elephant
The African Elephant, the world's biggest elephant. Wikimedia Commons

The largest land-dwelling mammal on earth, at seven tons, the African Elephant is an order of magnitude smaller than the Blue Whale (see slide #2) for a good reason: the buoyancy of water helps to counteract the Blue Whale's weight, and elephants are completely terrestrial. By the way, one of the reasons the African Elephant has such enormous ears is to help dissipate its internal body heat--a warm-blooded, seven-ton mammal generates a lot of calories in the course of the day.

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Biggest Dolphin - The Killer Whale (6 to 7 Tons)

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The Killer Whale, the world's biggest dolphin. Wikimedia Commons

The headline of this slide is a typo, right? How can the biggest dolphin be a whale? Well, the fact is that Killer Whales--also known as Orcas--are technically classified as dolphins rather than whales. At six or seven tons, male Orcas are much, much bigger than the biggest sharks alive today, which means that Killer Whales, rather than Great White Sharks, are the apex predators of the world's oceans. (The reason sharks, and not Orcas, have such a fearsome reputation is that very few humans have been killed and eaten by Killer Whales!)

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Biggest Even-Toed Ungulate - The Hippopotamus (5 tons)

The Hippopotamus, the world's biggest even-toed ungulate. Wikimedia Commons

The even-toed ungulates, or artiodactyls, are a widespread family of plant-eating mammals that includes deers, pigs, cows, and the biggest cleft-hoofed mammal all, the Common Hippopotamus, Hippopotamus amphibus. (A second Hippo species, the Pygmy Hippopotamus, Hexaprotodon liberiensis, doesn't even approach its cousin's five-ton heft.) If you want to be argumentative, though, you can also make an even-toed case for giraffes, which are much taller than hippos but only weigh about two tons.

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Biggest Odd-Toed Ungulate - The White Rhinoceros (5 tons)

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The White Rhinoceros, the world's biggest even-toed ungulate. Wikimedia Commons

Perissodactyls, or odd-toed ungulates, aren't quite as diverse as their even-toed cousins (see previous slide); this family consists of horses, zebras and tapirs on the one hand, and rhinoceroses on the other. And the biggest perissodactyl of them all is the White Rhinoceros, Ceratotherium simum, which at five tons rivals the size of Pleistocene rhinoceros ancestors like Elasmotherium. There are two types of white rhinos, the Southern White Rhinoceros and the Northern White Rhinoceros; we'll leave it to you to figure out in what part of Africa they reside.

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Biggest Pinniped - The Southern Elephant Seal (3-4 Tons)

southern elephant seal
The Southern Elephant Seal, the world's biggest pinniped. Wikimedia Commons

At up to four tons, not only is the Southern Elephant Seal the biggest pinniped alive today; it's also the biggest terrestrial meat-eating mammal, vastly outweighing even the largest lions, tigers and bears. As so often with pinnipeds, though, male Southern Elephant Seals vastly outweigh females, who tend to top at two tons, max. Like the Blue Whale (see slide #2), male Elephant Seals are also extraordinarily loud, as they like to bellow their sexual availability from literally miles away.

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Biggest Sirenian - The West Indian Manatee (1,300 Pounds)

west indian manatee
The West Indian Manatee, the world's biggest sirenian. Wikimedia Commons

The family of aquatic mammals that include manatees and dugongs, sirenians are only distantly related to pinnipeds (see previous slide), though they share many characteristics. At 13 feet long and 1,300 pounds, the West Indian Manatee is the world's biggest sirenian only by an accident of history: a much bigger member of this breed, Steller's Sea Cow, went extinct only 200 years ago, some full-grown individuals weighing as much as ten tons!

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Biggest Bear - The Polar Bear (1,000 Pounds)

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The Polar Bear, the world's biggest bear. Wikimedia Commons

If you're a fan of the Cartoon Network show We Bare Bears, you may be under the impression that Polar Bears, Grizzly Bears and Panda Bears are roughly comparable in size. Well, we hate to disillusion you, but Polar Bears are by far the biggest (and deadliest) ursines on the face of the earth: the largest males can rear up to a height of almost 10 feet and weigh well over half a ton. The only bear that even comes close is the Kodiak Bear of Alaska, some males of which can also exceed 1,000 pounds.

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Biggest Equid - Grevy's Zebra (1,000 Pounds)

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Grevy's Zebra, the world's biggest equid. Wikimedia Commons

The genus Equus comprises not only modern horses, but also donkeys, asses and zebras. While some domesticated horses tip the scales at over 2,000 pounds, Grevy's Zebra, Equus grevyi, is the world's largest wild equid, adults weighing close to half a ton. Like many of the other animals on this list, sadly, Grevy's Zebra is perched on the edge of extinction; there are probably less than 5,000 individuals occupying scattered habitats in Kenya and Ethiopia.

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Biggest Pig - The Giant Forest Hog (600 Pounds)

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The Giant Forest Hog, the world's biggest pig. Wikimedia Commons

Just how enormous is the Giant Forest Hog? Well, this 600-pound pig has been known to chase African Hyenas from their kill, and is itself sometimes preyed on by the largest African Leopards. Despite its size, though, the Giant Forest Hog has a relatively gentle disposition; this porker is easily tamed, if not outright domesticated, and can live alongside humans without too much blood being shed (it helps that Hylochoerus meinertzhageni is mostly a herbivore, only scavenging meals when it's especially hungry).

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Biggest Cat - The Siberian Tiger (500-600 Pounds)

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The Siberian Tiger, the world's biggest cat. Wikimedia Commons

In a way, it's good news that there are only 500 or so Siberian Tigers still extant in the far east of Russia: the males of this big cat weigh a whopping 500 to 600 pounds, females tipping the scales at a relatively svelte 300 to 400 pounds. However, continuing ecological pressure on the Siberian Tiger community may strip this big cat of its title; some naturalists claim that Bengal Tigers have already surpassed their Siberian relatives, since they're not quite as endangered and better fed (there may be as many as 2,000 Bengal Tigers in India and Bangladesh).

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Biggest Primate - The Eastern Lowland Gorilla (400 Pounds)

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The Eastern Lowland Gorilla, the world's biggest primate. Ehlers / iStockphoto.

There's a bit of a cage match going on in the "World's Largest Primate" competition, and the two contestants are the Eastern Lowland Gorilla and the Western Lowland Gorilla. Both of these gorilla subspecies live in the Congo, and by most accounts, the 400-pound-or-so Eastern variety has the edge on its 350-pound-or-so Western cousin. To be fair, though, Western Lowland Gorillas vastly outnumber the Eastern variety, by a 20 to 1 ratio, so if there are some plus-sized outliers in the Western Congo the trophy will be heading in that direction.

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Biggest Canid - The Gray Wolf (200 Pounds)

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The Gray Wolf, the world's biggest canid. Wikimedia Commons

Although some domesticated dog breeds grow to bigger sizes--have you ever house-sat a 250-pound American Mastiff?--the consistently beefiest species of genus Canis is the Gray Wolf, Canis lupus, full-grown individuals of which often reach 200 pounds. Unusually, Gray Wolves mate for life, which may have something to do with the serious repercussions if either partner is caught cheating--just imagine a 200-pound bundle of fur lunging at you with ared fangs!

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Biggest Marsupial - The Red Kangaroo (200 Pounds)

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The Red Kangaroo, the world's biggest marsupial. Wikimedia Commons

The size and weight of a full-grown human in dire need of a crash diet--about five and a half feet tall and 200 pounds--the Red Kangaroo of Australia is the largest living marsupial, which isn't saying much when you consider the enormous sizes of its ancestors. (Just to cite two Cenozoic examples, the Giant Short-Faced Kangaroo weighed 500 pounds, and the Giant Wombat tipped the scales at two tons.) Male Red Kangaroos are much bigger than females, and can cover almost 30 feet in a single leap!

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Biggest Rodent - The Capybara (150 Pounds)

The Capybara, the world's biggest rodent. Wikimedia Commons

You think the mice are big where you live? A full-grown Capybara, a South American rodent closely related to guinea pigs, tips the scales at 150 pounds, about the weight of an adult human. Believe it or not, though, the Capybara isn't the largest rodent that ever lived; that honor belongs to the Hippopotamus-sized Josephoartigasia, which weighed a whopping two tons (and presumably went completely unmolested by any Pleistocene mousetraps).

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Biggest Armadillo - The Giant Armadillo (100 Pounds)

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The Giant Armadillo, the world's biggest armadillo. Wikimedia Commons

Oh, how the mighty have fallen. During the Pleistocene epoch, armadillos were the size of Volkswagen Beetles--witness the one-ton Glyptodon, the abandoned shells of which were used by early humans to shelter from storms. Today, though, this comical-looking breed is represented in the record books by the 100-pound (and that's stretching it) Giant Armadillo of South America, which seems like a mere rounding error compared to its humongous ancestor.

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Biggest Lagomorph - The European Hare (15 Pounds)

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The European Hare, the world's biggest lagomorph. Wikimedia Commons

A bit like the killer bunny in Monty Python and the Holy Grail, only a bit less vicious, the 15-pound European Hare is by far the world's biggest lagomorph (a family of mammals that includes rabbits, hares and pikas). European Hares put their heft to good use: in the spring, females can be seen rearing back on their hind legs and swatting males in the face, either to refuse an invitation to mate or to see what kind of stuff their prospective mates are made of.

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Biggest Hedgehog - The Greater Moonrat (5 Pounds)

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The Greater Moonrat, the world's biggest hedgehog. Wikimedia Commons

There's a good reason you won't find the Greater Moonrat (Echinosurex gymnosa) in your local pet store. This five-pound hedgehog, native to Indonesia, emits a strong, ammonia-like odor, hisses menacingly to keep enemies at bay, and prefers to live alone, except during mating season (which, come to think of it, makes it vaguely reminiscent of your Uncle Stanley). Impressively, the Greater Moonrat isn't all that much smaller than Deinogalerix, a giant hedgehog of the Pleistocene epoch.

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Biggest Bat - The Golden-Capped Fruit Bat (3 Pounds)

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The Golden-Capped Fruit Bat, the world's biggest bat. Wikimedia Commons

"Megabat" is the evocative term naturalists use to describe any bat weighing more than a few ounces, and no megabat is more mega than the Golden-Capped Fruit Bat of the Philippines, also known as the Giant Golden-Capped Flying Fox. Fortunately for us humans, all fruit bats are strictly herbivorous--don't worry about a three-pound behemoth perching on your shoulder and attempting to suck your blood--and they also lack the ability to echolocate, making them the true gentle giants of the bat kingdom.

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Biggest Shrew - The Hispaniolan Solenodon (2 Pounds)

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The Hispaniolan Solenodon, the world's biggest shrew. Wikimedia Commons

"Hispaniolan Solenodon" doesn't exactly roll off the tongue, but you would never have any reason to name-check this shrew if you didn't live on Hispaniola, the island shared by Haiti and the Dominican Republic. The Solenodon can tip the scales at up to two pounds, which may not sound like much until you realize that the vast majority of shrews--a family of tiny mammals distinct from rodents--only weigh a few ounces soaking wet. Fortunately for this tasty, rotund lump of protein, Hispaniola is virtually bereft of any predators that could make the Hispaniolan Solenodon into a quick lunch.