Three Types of Mammals (Plus Examples for Each)

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The African elephants are the largest mammals on land. They can grow up to 3.3 meters in height and weigh around 13,000 pounds. They also walked the Earth around 200 million years ago. The title for the world’s largest mammal, however, belongs to a sea creature — the blue whale. It can grow to 30 meters in length and weigh around 400,000 pounds.

Aside from being the largest, the blue whale is also the world’s loudest animal. Its call can reach 188 decibels and can be heard over 500 miles away.

Three Main Types of Mammals

Marsupials (Pouched Mammals)

A part of the infraclass Marsupialia, marsupials have young that are born in a relatively undeveloped state. After the birth, the young marsupials called “joeys,” enclose themselves in the mother’s body in a special pouch. From there, they are developed further and also have access to the mother’s milk. The mothers’ pouches are specially designed to feed and carry the joey until it is ready to go out into the world. Although you can find some marsupials in the Americas, most are found in Australia.

Marsupials include the koala, Tasmanian devil, red kangaroo, wallabies, wombats, and Virginia opossum.

Monotremes (Egg-Laying Mammals)

Part of the order known as Monotremata, monotremes are the only mammals that don’t give birth to live young but instead lay eggs. Other than this, they are similar to other mammals in that they nurse their young with milk, are warm-blooded, have hair or fur, and have ears with three bones in the middle-ear section. Some scientists believe that these animals were “left behind” by some mammals that later became marsupials and placental mammals, which is why they still lay eggs like the reptiles do. Monotremes are the most primitive of all of the mammals, and they have features that resemble both reptiles and birds. These features include the hatching of eggs and having a single opening for the genital, digestive, and urinary organs.

There are five species of monotreme, which are the platypus and four types of echidna.

Placentals (Placental Mammals)

Placental mammals are a member of the infraclass known as Placentalia, and they give birth to live young. While the fetus is in the womb, it receives nourishment from an organ called the placenta. The placenta, in fact, is the most significant characteristic of placental mammals, and this organ facilitates the exchange of nutrients and wastes between the mother’s blood and the fetus’s blood. With the exception of marsupials and monotremes, all mammals are placental mammals. Humans are included in this category, as are tigers, blue whales, and vampire bats.

Examples of Mammals

Marsupials

1. Koala

A koala bear clinging on the branch of a tree.

Although a lot of people call these animals koala bears, they are not actual bears but instead are a type of marsupial. Koalas grow measure roughly three feet in length and can weigh anywhere from nine to 29 pounds. They are territorial animals that live close to one another in their own ranges. Since they have a tree-dwelling lifestyle, their physical features reflect this. These include two opposable digits and forepaws that are well-equipped to grip branches and pick eucalyptus leaves, which is where they get most of their nourishment from.

The soles of their feet are tough and textured and have long, sharp claws. Because of this, they get good traction and have strong thigh muscles so they can climb easily. In addition, a pad at the base of their spine that has cartilage in it and the thick fur on their bottoms allow koalas to sit on branches for hours at a time and remain comfortable. They also have a backbone that is curved and fewer pairs of ribs than most mammals – 11, not 13 – which creates a curled skeletal structure that makes it easier for them to fit into the forks of various trees.

2. Red Kangaroo

A red Kangaroo on the field.

The largest of all marsupials, red kangaroos measure roughly three to five feet long, weigh anywhere from 55 to 200 lbs., and have a tail that is between 2.5 and 4 feet long. The males are a reddish-brown color and have pale limbs and underside, while the females are small and are greyish in color. Red kangaroos are also equipped with hind limbs and feet that are very strong, short forelimbs, and a long, muscular tail. When red kangaroos want to move fast, they hop quickly on their hind limbs, using their tail to balance, and when they want to move more slowly, they use their tail like it is an extra limb and hop forward with their hind feet, taking their weight on their tail and forelimbs.

Red kangaroos live in the open savannahs and dry scrub areas of Australia, and they usually live alone or in small groups. They also sometimes gather together in bigger groups if resources are scarce. The red kangaroo lives mostly on grass and other vegetation, and they can go for a long time without drinking water because most of the moisture they need is found in the green plants that they eat.

3. Tasmanian Devil

A young Tasmanian devil in motion.

The Tasmanian devil is the largest carnivorous marsupial, with a body length of up to 32 inches and a tail that usually measures between 9 and 12 inches long. Weighing only 9 to 26 lbs., the Tasmanian devils are black in color and have a patch of white on their throat, as well as spots on their rump and their sides. They have a very stocky build and extremely large heads. Because of their diet, they have very heavy molar teeth and a strong jaw.

Tasmanian devils store fat in their tail, so if you ever see one of these creatures with a thin tail, it means that the Tasmanian devil is unhealthy. They have long whiskers that help them locate prey whenever they forage in the dark, but they also help the animal detect when other devils are nearby during feeding time. When Tasmanian devils get agitated, they often produce a very pungent odor that is so strong it can actually rival the odor of a skunk. Their senses are heightened, so they have a great sense of taste, smell, hearing, sight, and touch, and they can vocalize quite well when trying to communicate. This includes a screen that can be loud and quite eerie and growls that are aggressive, as well as physical gestures such as raising their tails and yawning.

The Tasmanian devil is found in dozens of habitats in Tasmania, Australia. They are mostly solitary, and their territories usually range from three to nearly eight square miles in size. Active at night, the Tasmanian devil spends the daytime hours hiding in a dense bush or a den.

4.Virginia Opossum

Virginia Opossum in the wild.

The Virginia opossum is one of over 60 species of opossums, and it has grey fur on its body and a face that is white and pointy. This opossum’s naked tail is quite unique because possums are the only mammal in the U.S. that have prehensile tails. They use these tails as a fifth limb for grasping things. Although some adult opossums are too heavy for the activity, most other possums spend a lot of their days in trees, with the young ones often hanging by their tails from the tree’s branches. Adult opossums usually grow to measure two to five feet long and weigh between 8 and 13 lbs., and they are the only mammal with four fingers and opposable thumbs on their hind feet.

Opossums are not picky eaters and adopt an omnivorous diet; in fact, they usually eat anything they can catch. They are scavengers that are attracted to carrion, and they frequently raid dumpsters and garbage cans located near dwellings in which humans live. One of their favorite foods is snakes, in part because they are immune to snake venom, so they can eat any type of snake. The opossum prefers farmland or wooded areas that have water close by, although they can adapt to almost any surroundings. They are transient creatures without any attachment to a specific den, and they sleep in any place that offers reasonable protection and is convenient for them.

5. Wallabies

A Wallaby standing on the ground.

The wallaby is similar to the kangaroo but still has distinct DNA and features. Some people call them a miniature kangaroo, but that isn’t an accurate description. Wallabies can jump very long distances and have long tails that help them balance. They are either white, grey, light brown, or black in color, and the front of their body is pure white. The wallaby has very large feet that have sharp claws on them, and their limbs, tips of the ears, and area around the eyes are darker in color. Like other marsupials, the wallaby has a pouch to nurse and care for their young.

A wallaby’s size varies significantly depending on where they live. They can grow to be anywhere from 12 to 41 inches long and have tails that can add another 10 to 30 inches to their length. Some wallabies weigh only 4 lbs., while others weigh about 50. Wallabies have very strong hind legs that enable them to jump high and far at the same time, sometimes up to 13 feet in one jump. Wallabies do not climb anything; however, the myth that they are able to climb still persists.

6. Wombats

A wombat in the grass land.

These are animals that are barrel-shaped, stocky, and short, and their physical advantages reflect their burrowing nature. Wombats have broad heads and small eyes, strong short necks, very small tails that are hidden by fur, and very powerful shoulders. They have coarse fur that can range from a glossy black to dark grey, and some even come in colors such as chocolate-brown, greyish-brown, silvery-grey, cream, and sandy. In southern Victoria, wombats that are albino or ash-white have been reported, and sometimes the soil can actually color the wombat’s coat. Clay soil, for example, can turn the coat red, and other types of soil can cause light patches to appear across their coat.

Wombats have one characteristic that sets them apart from other marsupials, and that is they have only two incisor teeth in their upper jaw. The molar and incisor teeth of the wombat are also very unique because they have open roots and keep growing throughout the animal’s lifetime. Common wombat features include a coarse thick coat, ears that are short and slightly rounded, and a nose that is large and naked.

It is impossible to generalize when it comes to a wombat’s size because their size can vary according to numerous factors. The island and Tasmanian wombats are a little smaller than other wombats, while female wombats, in general, are a little larger than males of the same age. Wombats have an average size of 33 to 45 inches, and they usually weigh between 48 to 86 lbs.

Monotreme

1. Echidna

An Echidna freely flaunting its spikes.

These monotremes are egg-laying mammals, and during the breeding season, the female develops a pouch where she lays and incubates her egg. Pouches, in fact, are fairly common with this type of mammal, because they are little more than a small fold of skin, and in fact, even males can develop a pouch. Male echidnas have a spur on their hind leg that is much like that of the platypus. However, unlike that of the platypus, the echidna’s spur is non-poisonous.

The echidna has a long spout that makes it easy for it to burrow for termites, ants, and worms, and sharp claws that are used for digging. This means that the echidna can dig efficiently thanks to its compact, muscular body shape and its strong forelegs. The echidna also has a long tongue that contains sticky saliva, which makes eating ants much easier.

Echidnas have spines that are actually made of modified hair, and they have long lifespans of up to 50 years if they are kept in captivity. One of their most interesting characteristics is that during the breeding season, male echidnas form mating trains whereby they line up nose to tail behind a single female and form a train that can contain up to a dozen individual echidnas. Although they nurse their young like other mammals, they do so without nipples, using special glands instead.

2. Platypus

A Platypus swimming freely.

A semi-aquatic, egg-laying mammal, the platypus is found mostly in eastern Australia, including in Tasmania. Along with all four species of the echidna, the platypus is one of the five existing species of monotremes and is the only type of mammal that lays eggs instead of birthing their young. In fact, the platypus is the sole remaining member of its family and genus, although in the fossil records there are a number of related species. Even more interesting, the first scientists to examine a preserved platypus actually thought it was a fake animal that was made up of several animals that were sewn together, which must’ve been an interesting observation.

The platypus is small and nocturnal, and it has short legs and webbed feet. Its feet each have five toes with very sharp claws, and a web-like fixture appears whenever it has to swim. The male platypus has a spur that is poisonous on its hind leg, and although this spur cannot kill a human being, it can cause great pain. They eat mostly crustaceans, snails, insect larvae, and annelid worms. They hunt for food underwater, where they can remain for up to five minutes.

Placental

1. Blue Whale

A blue whale swimming under the ocean.

The blue whale is part of the suborder known as Mysticeti, and is the largest animal alive, growing up to 100 feet long and weighing 150 tons or more. In addition to its massive size, the blue whale is also one of the loudest animals that exist today. In fact, when a blue whale calls, it can be heard far below the ocean’s surface, even from several miles away. Despite all of this, the blue whale eats mostly krill, which look like tiny shrimp.

The size of the blue whale prevents it from being attacked, except in rare circumstances. On those rare occasions, they are usually attacked by packs of hungry killer whales, although some humans hunt them during whaling season. When attacks do occur, the killer whale usually goes after a young, defenseless whale rather than an adult blue whale. Because blue whales can travel throughout the ocean without being hunted, they are known as apex predators, which is another way to say that they are predators with no predators of their own.

Contrary to what their name implies, blue whales are actually a greyish-blue color, but they look much bluer when underwater, thanks to the light from the sun and the color of the water. Although large, blue whales can swim up to 25 miles per hour or faster when they feel like they are being threatened, although their average speed is roughly 5 miles per hour.

2. Humans

A large family having a picnic on the park.

Humans have the same characteristics as other mammals but enjoy some unique characteristics as well. Humans use tools to gather food or kill animals, can stand upright, and have evolving body shapes of many different sizes and types. Their brains are continuously growing bigger and more complex, they use language and symbols, and they have developed a social system.

Humans have many characteristics related to consciousness as well, including an introspective mind which can question purpose and existence and a pronounced self-awareness. They can act unjustifiably superior to other species and are able to imagine and create things which were previously non-existent, have intensive relationships, and feel distinct emotions. All of these things set them apart from other mammals, and they are just a few of the things that make humans truly unique.

3. Tiger

A tiger looking calm in the wild.

Of the entire cat species, tigers are the largest. They are also most recognizable for their pattern of dark vertical stripes and reddish-orange fur with a lighter underside. A part of the genus Panthera – which also includes the jaguar, leopard, lion, and snow leopard – the tiger is an apex predator, and they mostly prey on animals such as bovids and deer. The tiger is territorial and both solitary and social. Because of these and many other reasons, tigers and humans have often experienced conflicts of various types.

Although it is common for adult male tigers to be aggressive, this aggressiveness can be influenced by many things. This includes the density of tigers, or the number of them found in a given area, and whether there is a disruption socially whereby males are competing to take control of a certain territory. They are more intensely aggressive when there is a high tiger density in an area simply because there is more competition regarding mating opportunities and resources. The males who hold their territory even occasionally challenge one another if the resident male dies or leaves the area. In these instances, the strongest male usually takes possession of the territory, and when there is much social disruption, the female tigers can also get aggressive.

4. Vampire Bat

Two vampire bats hanging on a cave.

Although bats are the only mammal that can fly, they have one other interesting characteristic, and that is that bats are also the only mammals that feed entirely on blood. They sleep during the day suspended upside down from the roofs of caves, and they are in total darkness when doing so. They generally gather in colonies of approximately 100 bats, although sometimes their groups can total over 1,000. In any given year, a colony of 100 bats can drink the blood of roughly 25 cows.

Bats leave their caves during the darkest part of the night, and their victims typically include sleeping horses and cattle, although they have been known to feed on humans at times. For roughly 30 minutes, the bat drinks its victim’s blood, and even though they don’t necessarily drink enough of it to harm the host, their bites can still result in diseases and nasty infections. They have few teeth, but the ones they have are extra-sharp, making this drinking of blood very easy for them to do.

When vampire bats are young, they feed on milk, not blood. Even when they are in flight, young bats cling to their mothers and consume nothing but milk for roughly three months. The vampire bat is found mostly in Central America, South America, and the tropics of Mexico.