Shark Species

Are Sharks Mammals or Do They Lay Eggs

People who are fascinated by marine life, specifically their types and classification, often wonder if sharks are mammals or if they lay eggs. A huge variety of marine animals lay eggs, and at the same time, several marine animals give live birth, but not much is clear about the sharks. On the other hand, sharks alone do not have one type, but you will find hundreds of species in all parts of the world.

So it becomes more difficult to identify whether sharks are mammals or do they lay eggs. But if you are curious about it and want to know the answer, let’s read the article to the end, and you will be over all the technicalities.

We consider mammals warm-blooded vertebrates that are capable of producing milk for their young. If we look at this definition, the sharks will be disregarded and will not lie in the category of mammals. Categorically, sharks are out as being classified as mammals. However, all species of sharks lie in the fish category.

This is due to the fact that sharks do not consist of mammary glands, nor do they feed their babies, but just like the fish, they have gills through which they breathe. When it’s crystal clear, why are sharks often mistaken for mammals? Well, let’s find out.

Why are sharks sometimes misidentified as mammals?

It’s not whether an animal lays eggs or gives birth to its young that makes it a mammal, which is often believed, and it is the primary reason sharks are identified as mammals, but, to be accurate, it’s not exactly how it is. There are exceptions in this case, and sharks are one of them.

Sharks do not always lay eggs, which is a common trait of non-mammals, like most species of fish. However, there are certain shark species that lay eggs. Sharks lay eggs within their mother’s body, but after many eggs are laid, they hatch outside the mother’s body without parental care and are eventually born as developed pups.

In the case of mammals, some sharks do give birth to live young, and they are often regarded as viviparous. On the other hand, the sharks that lay eggs are referred to as oviparous.

That is one reason why the presence of an egg is not necessarily a determinant of whether an animal belongs to a mammal class or not. When it comes to sharks, we have both the categories, egg-laying sharks and the sharks that give birth to live babies.

Whatever the case is, sharks are not labeled as mammals. So, answering the main questions, some sharks lay eggs, while some sharks give live birth, but none of them are mammals.

This further creates doubts, but below, we are going to see a few more facts that will help us understand why sharks are classified as fish and not as mammals.

Why are sharks not recognized as mammals?

There are multiple reasons that can justify sharks as fish but not as mammals. Whether it is egg-laying sharks or the ones producing babies, sharks are not mammals, and the points discussed below give further justifications.

Sharks do not produce milk

As for mammals, they feed their babies with milk, but when you look at the sharks, neither do they produce milk nor do they feed their babies. Moreover, you will hardly see any parental care with regard to sharks.

Mammals are warm-blooded

Warm-blooded means having the capability to maintain an even body temperature, but when it comes to sharks, they are regarded as cold-blooded. In other words, sharks cannot regulate their own body temperatures. Cold-blooded organisms, on the other hand, rely on external factors to maintain heat or cold as they require.   

Breathing difference

When it comes to mammals, their breathing method acts as an identifying factor, which is due to the fact that mammals breathe through their lungs. However sharks do not have lungs, but they breathe through gills.

This is another defining factor that clarifies sharks are not mammals.

Besides these points, there are a few other crucial characteristics that help define the category of mammals. For example, mammals have hair on their bodies and have three ear bones. But none of this fits on the shark.

Considering all of this, the only point that shark matches with mammals is that sharks do give live births, but that alone is not enough to declare sharks as mammals. You will find sharks giving birth to live young and as well as sharks that lay eggs.


When it comes to sharks, you will see both types. For example, the bullhead, carpet, and bamboo sharks are said to be egg-laying sharks, whereas blue sharks and lemon sharks give live birth. However, not any shark species can be identified as mammals. Though it’s a popular belief, what is not true is not true. Do check out the reasons above, and your confusion will be gone. 

About the author

Ameer Hamza

Ameer Hamza is a well-versed content writer who has been a part of the writing industry for over 4 years and part of Talha Saif Enterprises as an Author for over a year. Through his love of writing, he has developed his own writing style. He enjoys writing articles and blog posts that provide readers with detailed and accurate information. The knowledge he gained from his education helped him tackle many different subjects without any problem. As an avid reader and technology geek, Ameer is always on the lookout for the latest innovations.