Is A Shark A Fish Or A Mammal? Myths And Facts About Shark | Kidadl


Is A Shark A Fish Or A Mammal? Myths And Facts About Shark

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Sharks are among the most fascinating creatures in the ocean.

Sharks do have a specific fish name known as elasmobranchs. There are different types of sharks found.

Sharks can vary in size depending on the type of shark. There are even aquarium shark fish that grow up to two feet in size. These aquarium sharks are all friendly like other fish. You may be surprised to know that sharks do not have bones. Isn't it interesting? If sharks do not have bones in their body, then what are these big creatures made of? Well, it is to be noted that sharks are made up of cartilaginous tissues. The term 'elasmobranchs', which is used for sharks, is also indicative of the tissues in their bodies. There are different varieties of sharks, for example, white sharks.

These big creatures also have another characteristic that is worth noticing. A shark is a cartilage marine animal that humans are afraid of. Chondrichthyes is the class referring to such fish. Sharks are great predators but are still fearful. You may be surprised to know that sharks do have many fears. Researchers have found that dolphins are the species that make sharks scared. Orcas are known to be scary for sharks too. Sharks are even known to be afraid of humans.

Sharks are known to have hundreds of teeth, with almost three hundred in their mouths! Another interesting thing is that sharks do not have very strong roots. A shark tooth is not meant to have roots.

There are other exciting facts about this great animal. Sharks' skeletons are made out of cartilage, making them cartilaginous fish, not mammals.

So, are sharks mammals? Or is it true that sharks are fish? The answer is that sharks are known to be fish rather than mammals. Sharks do not have any mammalian features in their bodies. Sharks are known to be cold-blooded fish. Hence, the anatomy of a shark shows that sharks are not mammals but are considered fish without bones. It is a myth that many people believe that sharks are mammals.

Are you enjoying learning about whether sharks are fish or mammals? Then why not learn about animals in the Arctic or how long whales are pregnant?

Are sharks mammals or fish?

As already discussed above, sharks are fish, meaning that sharks are not mammals.

Mammals are from the mammalian group and are categorized under the vertebrate group. Mammals have some exceptional body features, which can be used to tell if an animal is a mammal. The most known fact about mammals is the presence of mammary glands. Hairs on the body, a warm-blooded nature, having backbones and having a developed brain are all the characteristic features of mammals. Sharks are not warm-blooded, and these species do not breathe through lungs. However, they do need oxygen for survival. This fish absorbs oxygen from water.

Another common myth about sharks is confusion among people about sharks being amphibians. Sharks are cold-blooded, and they are not mammals, but they do not possess amphibian qualities. Sharks are pure cartilaginous fish species, probably a million years old, and tend to use gills to breathe air throughout their life. Hence, it is truly false to consider sharks to be amphibians.

So what about dolphins? Are dolphins mammals or fishes? Dolphins are purely mammals. Dolphins show a great range of mammalian characters. For example, dolphins are warm-blooded animals, and they are equally a million years old. Dolphins, unlike fish, do not breathe air through gills like other fish. Dolphins have lungs to breathe. You may be surprised to know that dolphins jump out of the water to breathe air too. These cute, friendly animals are purely mammals.

Why Sharks Are Fish

Since sharks are regarded as sea species and not mammals or amphibians, it becomes common to wonder why sharks are called fish.

The answer is that sharks possess all fish qualities. Sharks are known to have gills and breathe air through gills.

What kind of fish is a shark?

Another curious question among people is regarding what type of fish sharks are. Sharks are special types of fish.

This is because a shark's body is not made out of a skeleton. It is important to note that a shark's body is made up of cartilage tissues. Sharks come under 'elasmobranchs', which is a classification made up of cartilaginous fish. Other fish included under this category are sawfishes and skates.

Another unique aspect about sharks, apart from their ability to maintain their body temperature, is that they contain capillaries. They are used to absorb oxygen from the water and then release carbon dioxide. They breathe just like humans, and they function in the same as our lungs and like other fish. Those glands take in 80% of the oxygen concentration present in water.

Tiger Shark swimming over the seabed.

How do sharks give birth?

Sharks are fish, not mammals, but sharks do have a unique egg-laying feature. These cartilaginous fish are ovoviviparous. Sharks lay eggs inside their bodies.

A common question is whether the eggs hatch inside a shark's body. Well, the answer is a big yes. Eggs hatch into young babies that remain inside the mother shark. After some days, mother sharks release their young ones out from their bodies. Sharks produce pups.

Like many other fish species, sharks give birth to baby sharks, and we call them pups. Some fish, including sharks, give birth to 20 pups in a litter. However, they do not have mammary glands, even though this species can give birth to young. They are unable to feed the young sharks that they produce. They search for prey to feed to their young, compensating for the absence of mammary glands. For those who are wondering if sharks lay eggs, no, they give birth to pups with neat fins and gills. They also swim around in search of food to feed their little ones.

What makes a marine mammal different from sharks and other fish?

There are marine animals that are mammals and fish. For example, sharks are fish, and dolphins are mammals. So, since all these marine animals live under the water, it is easy to wonder about the differences between these two marine creatures.

Sharks and any other fish are cold-blooded animals, whereas marine mammals are warm-blooded animals, which is a characteristic of mammals. Also, fish and sharks have scales on their bodies, but this is not evident in the case of mammals. The body of a marine mammal is covered with hair. The biggest difference is the birth process. Marine mammals nurture their young ones. This is not seen in fish, as fish tend to lay eggs. Even sharks have a different style of raising their young.

Sharks are cold-blooded animals, predators, and opportunistic feeders. They belong to the ocean, so they prey on any smaller fish and invertebrates available. Larger fish sharks feed on seals and sea lions. You may have seen sharks swim all around the sea but have you ever thought of the temperature they maintain. Sharks, like the fish shark, great white shark or whale shark species, regulate their internal body temperature and reach higher than their sea surroundings. These species have specific blood vessel arrangements.

Sharks swim, and their swimming looks more like flying. Some species, like the great white shark, use their tail to propel themself but most think it is related to their fins. Fins, however, are just for balance, unlike the tail. Also, whales move side to side instead of using a tail. While we are on the topic of swimming, we might as well learn a thing or two about bones. Whales have real bones. Their skeleton has a backbone, rib cage, and all of it. Like human lungs, whales have human-like arm bones too.

Sharks are often misunderstood as mammals, while sharks are actually true fish. The main reason behind the confusion of a shark being a mammal or a fish is its birthing nature. Since a shark gives birth to young ones, many people tend to think of sharks as mammals. But this is not the case. A shark is made up of cartilage and is an ovoviviparous animal. Mother sharks are known to lay eggs inside their own body. Hence, the hatching of young sharks also occurs inside the body. After hatching, the mother shark lets the baby out.

Hence, sharks are often thought to be mammals. But in reality, it is the ovoviviparous nature of sharks that makes people misunderstand these big creatures as mammals. Sharks are wild creatures. White sharks are being preserved today. When whales are sharks are not scared of humans hurting them, or if they are not giving birth, these sharks can be the loveliest creatures. There have been many cases and stories where sharks are known to save human lives. Sharks even are helpful and tend to have excellent eyesight.

Another interesting thing about sharks is that sharks do not sleep. This means that, like humans or other fish, sharks do not show characteristics of sleeping. Sharks have a unique sleeping way which is known to be an active but restless stage. The earth has many wonderful creatures to adore. Sharks are some of the wonderful creatures created who are often seen as aggressive marine animals because of their predatory habits.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for 'Is a shark a fish or a mammal?' then why not take a look at 'Facts about coral reefs', or 'how long do dolphins live'?


The Kidadl Team is made up of people from different walks of life, from different families and backgrounds, each with unique experiences and nuggets of wisdom to share with you. From lino cutting to surfing to children’s mental health, their hobbies and interests range far and wide. They are passionate about turning your everyday moments into memories and bringing you inspiring ideas to have fun with your family.

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