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9 Animals That Are Warm Blooded (Fun Facts)

Warm-blooded animals, also known as endotherms, are able to self-regulate their body temperature. Animals that are warm blooded must maintain a certain internal body temperature at all times, such as humans an our average of 98.6 degrees F. This is mainly accomplished by our metabolism and covering the food we eat into energy and body heat. Cold blooded animals are not able to maintain a constant body heat. Their internal temperature is dependent on the environment around them. Animals that are warm blooded include mammals and birds, so while we can’t list all the birds and mammals out there we will take a look at 9 categories of animals that are warm blooded.

Photo collage animals that are warm blooded

Animals that are warm blooded

1. Birds


There are roughly 9000-1000 species of birds across the globe. While this number seems low compared to insects or fish, birds are very interesting animals that have evolved to thrive in just about any environment. From penguins in sub-zero temperatures to roadrunners in the Sonoran desert, birds are able to thrive and keep their body temperatures right where they need to be.

Birds have evolved several means of keeping warm in cold temperatures. Reminiscent of their dinosaur heritage, many bird species have scales on their feet and legs that help them stay insulated and warm in cold weather. In addition to this, they also have their feathers. Bird feathers are designed to have a water-resistant top layer and a downy warm under layer. They use these layers in the cold to trap pockets of air between their feathers. They then warm the air and themselves by shivering.

This is why it’s very important that birds keep their feathers clean and preened. Dirty or poorly kept feathers are not able to insulate birds properly or keep them dry. This is one reason why oil spills can be so devastating to bird populations.

In hot weather, birds stay cool by bathing in water and then spreading their wings and shaking. As the water evaporates, it takes heat with it and wind moving through the bird’s feathers also helps to dissipate heat. When water isn’t available, birds can also open their mouths and allow wind to pass through their beak. As the saliva evaporates, so does heat, allowing the birds to drop their temperatures.

2. Bears

Bears are large mammals and members of the family Ursidae. In general bears have a bulky, robust body, round ears and short tails. They don’t have super long limbs as they are built more for strength than for speed, but can move quickly for short distances. There are eight bears worldwide, the brown bear, polar bear, Asian black bear, American black bear, sun bear, sloth bear, spectacled bear and giant panda.

Bears have a great sense of smell and they use this as one of the main ways they locate food. Speaking of food, they have quite a diverse diet. Most bears will eat a mixture of meat, leaves, roots, berries and fish. There are also extremes, such as the Panda who’s diet is almost entirely plant based (bamboo), and the Polar Bear who’s diet is mainly meat (seals).

Bears have short dense hairs close to the skin that trap heat, and grow a shaggy layer of longer outer hairs during cold weather. Some bears, such as the American black bear and grizzly bear, will hibernate in the winter. Hibernation is a state where the bears metabolism and heart rate lowers in order to slow their metabolism down and conserve energy. During this period they are basically asleep and do not need to eat, drink or go to the bathroom. If the weather gets too hot, bears can pant, find shade, lie on cool surfaces, and take a dip in water to help cool down.

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Polar bears live in one of the coldest climates on earth. Some extra adaptations they have that allows this is they have a layer of blubber under their skin. Blubber is more insulating than regular fat. They also have two coats of thick fur, and their skin is black and can absorb UV rays and trap heat.

3. Whales

A group of humpback whales exhaling through their blowholes

Whales are large, warm-blooded aquatic mammals that live their whole life in the open ocean. Whales can range in size from the smaller dwarf sperm whale (8.5 ft long) to the huge 98 foot blue whale. You may think the largest toothed predator on earth is a lion or a bear, but nope, it’s the sperm whale. But not all whales have teeth. Toothed-whales can catch squid and fish. Whales with long plates of baleen filter krill and plankton out of the water.

Whales used to be land mammals, and still need to breath air from the surface of the water. They can stay underwater for long periods of time, some over an hour, but they all must come to the surface and take in air through a blow-hole at the top of their head.

To stay warm, all whales have a thick layer of blubber. Blubber is different than the body fat of other animals in that it is thicker and contains more blood vessels. In whale species that live in very cold water, near the poles, their blubber can be almost a foot thick to help them retain heat. Many whales migrate throughout the season and can travel to more temperate waters.

4. Big Cats

“Big cats” is a blanket term used to describe the five members of the Panthera family. This includes tigers, lions, jaguars, leopards, cheetahs and cougars. All big cats are warm blooded, and so is your pet cat! Despite their differences, most cat have very similar body structure and behaviors, except for the cheetah who is specially adapted for its lightning fast speed. All cats are carnivores, and many of the big cats are considered the apex predator in their environment. They have sharp teeth and strong, sharp claws to aid them in killing and eating their prey.

Some big cats live in the heat, such as lions in Africa. To keep cool, the big cats can hunt in the cooler morning and evening hours and rest in the shade during the afternoon. Panting also help release excess heat. On the other hand there are big cats that live in cold and snowy climates, such as snow leopards. These big cats grow super thick layers of fur that trap heat close to their body. They can even grow fur on the bottom of their paws to insulate against walking in the snow.

5. Deer

fallow deer

Deer are four legged, hoofed mammals of the family Cervidae. There are many species of deer such as the white-tailed and mule deer. However elk, caribou (reindeer) and moose are also members of the deer family. With the exception of the Chinese water deer, all male members of the deer family grow and shed a new pair of antlers each year. These antlers can be used for protection, however they are mainly used in male to male combat to fight for dominance during mating season. Deer can live in a variety of habitats and are found on every continent except Antarctica and Australia. They are often important prey species for larger carnivores such as big cats and wolves.

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To deal with summer heat, deer can pant like dogs. They also have long ears full of veins that will help disperse heat from their body. Deer will also seek shade lay on the ground to avoid overheating.

Other deer, such as the reindeer, live in very cold climates. They are able to keep warm by having two layers of fur. There is a fine and dense layer next to the skin, and a shaggier, longer layer over that for insulation. During summer they can molt off this heavy coat, then grow a new one as the next winter approaches. The nose of a reindeer also has a heat exchange system that helps warm the air on the way into the lungs.

6. Marsupials

A marsupial is a type of mammal that gives birth to a newborn that is not yet fully developed. After birth, the mother carries it in a special external pouch until the baby has matured enough to live outside of her body. This is different than the vast majority of mammals, who are “placental”. Placental mammals, which includes humans, do not give birth to their young until they are fully developed. Some of the best known marsupials include koala bears, kangaroos, Tasmanian devils, wombats and opossums.

A newborn marsupial is called a “joey”. Since joeys are underdeveloped and born with no fur, they are unable to regulate their own body temperature. Joeys must remain in their mothers pouch, which is kept at 86-90 degrees F, until they have grown all their fur and fully developed.

The opossum survives the cold North American winter by creating a den lined with leaves, grasses and soft materials. They don’t hibernate but will spend a lot of time curled up in the insulated nest to keep warm. On the other side of the world, the Koala lives in the heat of Australia, and can’t even sweat to stay cool. So instead they hug trees! Many trees are actually cooler than the surrounding air, and koalas will lay across the branches for some cooling relief.

7. Rodents

Mice, squirrels, rats, porcupines, hamsters, beavers and prairie dogs are all examples of rodents. All rodents have very sharp incisor teeth that continuously grow. The rodent must wear down these teeth by gnawing on tough surfaces to keep them at an appropriate length. This is accomplished by cracking seeds open for food, excavating burrows to live in, or chewing wood. While some rodents are medium sized, most are fairly small. They often live in social groups, and are one of the most widespread groups of mammals, living on every continent except for Antarctica. They are an important prey animal for many creatures such as foxes, bobcats and owls. Some rodents such as the beaver are considered keystone species and can shape the entire ecosystem.

Many rodents survive cold winters by nesting in closed spaces. Burrows lined with plant material make a cozy den. They also collect and cache nuts and seeds to ensure they can keep on enough body fat. Beavers actually store fat in their tail that they will use during the winter, and spend most of the time inside their insulated lodge where they have stored food.

8. Primates

The group of mammals known as primates includes monkeys, lemurs, lorises, orangutans, gorillas, chimpanzees and humans. Relative to their body size, primates have large brains giving them advanced problem solving capabilities and intelligence. Primates also rely more on their eyesight than most mammals, whose main sense is smell. They also often live in groups with complex social systems. Except for humans who are bipedal, many primates rely on four limbs for locomotion and often a tail for additional grip and balance.

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Like humans, monkeys can sweat when overheated to help cool down. They can also seek shade and water to find some relief from heat. The majority of species live in areas that don’t get too cold, however monkeys will seek shelter and huddle together to use body heat if it gets cold. The monkeys that live the furthest north, Japanese snow monkeys, actually dunk in hot springs to help stay warm during the winter.

9. Humans

As mammals and primates we have similar physical ways of regulating our body temperature as other animals, sweating, seeking shade and shelter. However we have also created our own methods of altering our environments to keep ourselves warm and cold. For one, while we certainly don’t have enough body hair to keep ourselves warm, we have invented all sort of different fabrics to clothe ourselves to both cool us down and warm us up.

The invention of fire was man’s first foray into creating heat for himself. Fire not only helped us to stay warm, but it also kept us safe from predation and provided light for early hunter-gatherers to see. This allowed them more time to work on things like tools, clothes, and even art that they may not have had time for before.

While we still utilize fires to keep warm while camping or in fireplaces in the winter, we also now have gas and eclectic heating systems in most of our homes.

To keep cool, we have invented fans, air conditioning systems, and pools. We have come a long way from our spear-wielding ancestors. We can now regulate the temperatures of our homes and our cars to be as warm or as cold as we want them.

2 “Almost” Warm Blooded Species

These two interesting creatures are not technically warm blooded, however they have evolved certain abilities to help regulate their own body temperature that is different than other cold blooded creatures.

1. Tuna 

image by National Marine Sanctuaries via Flickr

While tuna aren’t truly warm-blooded like some animals on this list they are able to regulate the temperature in their organs and swimming muscles. This allows them to put on bursts of speed while swimming. It is thought that while most fish need time to warm up while accelerating, tuna’s already warm muscles are able to go from 0 to 30mph very quickly.

One area not heated on tuna are their gills. It is thought that the reason for this is that water passing through the gills already provides them with heat, so having heated gills would be a waste of much-needed energy.

2. Lamnid Sharks

Lamnid sharks also known as mackerel sharks also have some endothermic abilities. This group of sharks includes the short-fin mako, long-fin mako, salmon, porbeagle, and everyone’s favorite to fear, the great white.

These sharks have a system in their body called counter-current exchange. It allows them to raise the temperature of their muscles 10-15 degrees in order to give themselves bursts of speed. They use this speed to help them be more successful when hunting or escaping predators.