Scientifically-speaking there are 11 mammal groups, and most Mammals are warm-blooded, have body hair, give live birth and nurse their young with milk from mammary glands. Check out these articles about all kinds of mammals.
Leopard Seals Are Apex Predators of the Antarctic
With Fewer Than 10 Left, Can the Vaquita Be Saved?
Humpback Whales Have Made an Amazing Comeback From Extinction
Baby Bats Babble With Moms, Hinting at Human Language Development
Fruit Bats Are the Best Pollinators (and Suppliers of Tequila)
Brazilian Free-tailed Bats Are Way Faster Than We Thought
Alaska's Kodiak Bear Is One of the Planet's Biggest
What's the Difference Between a Brown Bear and a Black Bear?
How Polar Bears Work
Gray Wolves Will Get Federal Protection Again in Much of U.S.
The Serval Stands Tall and Jumps Like A Champion
Are Dingoes Dangerous (and Did One Really Eat a Baby)?
Dik-dik: The Tiny Antelope With the Embarrassing Name
Are Mules, Burros and Jackasses All Donkeys?
Tapir: The Ancient Fruitarian With the Tiny Trunk
What's It Like Inside a Kangaroo's Pouch?
Do Kangaroos Really Box?
The Smiley Quokka Is an Australian Super Survivor
The Tarsier Is One Weird Primate, and Yes, We're Related
Marmosets Are Tiny, Upper Canopy-dwelling Monkeys
Why Do Gorillas Beat Their Chests?
How Long Do Squirrels Live?
'Splooting': It's What All the Cool Squirrels Are Doing This Summer
Squirrels Get Jacked During Hibernation; No Weights Needed!
World's Largest Wolves by Weight: The Mighty and the At-Risk
The Pink Fairy Armadillo Is as Mystifying as Its Name
The Coatimundi Is Cute But Doesn't Make a Good Pet
The world's largest wolves weigh up to 175 pounds (79.4 kilograms) and measure up to 6 feet (1.8 meters) in length.
The pink fairy armadillo looks like something out of a children's book and is so rare that very few people have ever seen one.
By Carrie Tatro
You don't want an animal living in your house that's smarter than a raccoon and never rests.
Don't freak out with worry if you see a splooting squirrel — he's just cooling off in the best way he knows how.
Never heard of the tarsier? Well it's one of the smallest primates in the world but has some of the biggest bug eyes you've ever seen.
An orangutan who could unscrew bolts to bust out? A gorilla who climbed the vines out of her enclosure to just roam the zoo? These are wild animals, and these are their wild escape stories.
Pine martens are elusive and love to stay hidden in deep forests, but with strong claws, they are great climbers and hunters.
By Katie Carman
A federal judge reversed a Trump administration ruling that removed the gray wolf from the Endangered Species Act. Here's why.
By Logan Smith
Kodiak bears are some of the largest bears in the world and live only in the islands of the Kodiak Archipelago in Alaska.
Hibernating mammals like ground squirrels can build some muscle mass during their big sleep, with the help of gut bacteria.
The adorable vaquita, the world's smallest porpoise and rarest marine mammal, has been pushed to virtual extinction by greed and fishing nets.
By Katie Carman
Scientists have found striking parallels between the babbling produced by greater sac-winged bat pups and the babbling baby sounds of human infants.
Leucistic squirrels are rare, but Brevard, North Carolina has a thriving population.
You read that right. Fruit bats are instrumental in pollinating hundreds of plants, including the agave, a key ingredient in tequila.
By Mark Mancini
With a little pig snout and the locomotion of a kangaroo, these tiny desert rodents hardly ever drink water and rarely urinate.
Humpback whales can be as long as a city bus and weigh as much as two. They love to breach and water slap with their fins and tails, making them a perennial favorite for whale watchers.
By Katie Carman
They look a lot like beavers and the two rodents have a lot in common. But muskrats are their own species with their own signature scent.
By Meg Sparwath