So, you are interested in finding out whether fish can be considered mammals or not.
In this article, you’ll find the exact answer to this question and you’ll also find answers to a few more closely related questions.
So, make sure you keep on reading this article till the end.
Is a fish considered to be a mammal?
In the animal classification, among the vertebrates, exists a phylum called Chordata, to which fish belong to.
Fish, as members of the Chordata phylum, share with other vertebrates several characteristics.
These features include but are not limited to them having a notochord at some stage in their life, gills, or skeleton, a posterior dished nerve ligature, and also a tail.
Fish are divided into five groups, each as unique as the four recognized groups of animals: reptiles, birds, mammals, and amphibians.
Mammals, on the other hand, are living creatures distinct for having hair and fur, and females can produce milk to sustain their young and most importantly deliver live young.
Fish do not have any hair or fur, rather their bodies are covered in scales, they are also egg-laying, do not have limbs, and also most of them are cold-blooded.
Check out the video below if you want to find out a bit more about mammals.
Is a goldfish considered to be a mammal?
Goldfish aren’t considered to be mammals.
They are, however, identified as fish.
The goldfish is of the family Cyprinidae of the order Cypriniformes, which live in freshwater environments.
They possess fins which are their pelvic fins and their pectoral fins.
These are the two sets of paired fins seen on goldfish.
They breed by laying adhesive eggs that attach themselves to aquatic vegetation.
Mammals are not known for laying eggs, only a few mammal species are exceptions to this rule.
Fish also breathe through their gills, unlike mammals who have lungs.
Is a pufferfish considered to be a mammal?
A pufferfish is most definitely not a mammal.
It is a fish from the Tetraodontidae family of the order Tetraodontiformes.
The majority of them are marine water fish but there are a few exceptions.
They possess spines on their body for protection.
They also lay eggs just like all other fish, a feature that when combined with being cold-blooded and breathing through gills set them apart from mammalian animals.
Is a dogfish considered to be a mammal?
The dogfish, also known as the mud shark, or spurdog, is a fish rather than a mammal.
It belongs to the Squalidae family of the order Squaliformes.
These marine water fish are distinct in that they possess a dual spine and no anal fin.
They too are egg-laying, cold-blooded, and they breathe through their gills which is also why they’re seen as fish and not as mammals.
Is a shark considered to be a mammal?
Sharks are also fish as opposed to mammals.
These marine water fish belong to the family Lamnidae of the order Lamniformes.
Unlike most other members of the fish family, most species of sharks give birth to live young, referred to as pups.
Cat sharks are among the few shark species that lay eggs.
Sharks are also special fish in that their body is made out of cartilage rather than bones.
They however possess features that distinctly belong to fish, like only being able to survive in water environments and being able to filter oxygen from water by using their six to seven gills located on each side of their heads.
All this put into consideration, sharks remain under the fish category.
Is a whale shark considered to be a mammal?
A whale shark is also surprisingly a fish and not a mammal.
It belongs to the Rhincodontidae family of the order Orectolobiformes.
These are also marine water fish, famous for their many records with regards to their size in the non-mammalian vertebrate world.
They breed via internal fertilization and they give birth to live young.
They are filter feeders meaning they open their mouths wide open and then catch their prey whilst filtering out the water.
They also breathe by filtering oxygen from water with their gills, and they are cold-blooded, making them fish and not mammals.
Is a whale considered to be a mammal?
As interesting as it may seem, whales are mammals. Not fish.
These large fish belong to the Cetacean family of the order Cetacea.
Whales possess several distinct characteristics that set them apart from fish and place them into the mammalian group.
These features include being warm-blooded just like mammals, whilst fish remain cold-blooded, giving birth to live young, and breathing air through their lungs like humans and other mammals do.
Also, most fish species have tails that sway from side to side but whales have a tail that sways up and down instead.
Thus, whales are no fish.
Is a dolphin considered to be a mammal?
Next on, dolphins.
These join whales in the mammalian group of animals.
They belong to the Delphinidae family of the order Artiodactyla.
Unlike fish, dolphins breathe air through their lungs and thus have to make periodic trips to the surface to breathe.
They possess a nostril on their head (blowhole) to facilitate surfacing to catch a breath.
They are also warm-blooded.
All these factors combined leave the dolphins in the mammal group rather than the fish group.
Why is a fish not considered to be a mammal?
Generally, fish cannot be considered mammals, since most of them are cold-blooded, do not possess hair, fur, fingers, limbs, or even toes, and they do not breathe through lungs like mammals instead they breathe through their gills.
Besides, most fish species are unable to give live birth and they’re also unable to produce milk for their young which are both features that can be found in mammals.
Mammals also have a more complex brain than fish which is another feature that sets them apart from one another.
Is a fish considered to be a reptile and why?
Fish are not considered to be reptiles.
Various fish species instead are classified as fish because they contain all the characteristics that are required to classify them as such.
Although fish, like reptiles, are vertebrates, lay eggs, are cold-blooded, and have bodies that are covered in scales, there exist several distinct differences between the two animal groups.
Fish, for example, have gills for breathing underwater, fins for moving through the water, and fish live their lives in water environments.
Pretty much every reptile has limbs whilst fish lack this characteristic and every reptile species that can be found on this earth has at least one lung as well which cannot be found in any fish species.
Is a fish considered to be an amphibian and why?
Fish are not considered to be amphibians because fish themselves do not contain the characteristics that are required to classify them as such.
Fish, for example, cannot breathe through their skins, don’t have a complex life cycle, and do not have lungs.
Besides, fish are unable to live on both lands and in water environments which is the case for amphibians.
Fish also have bodies covered in scales whilst amphibians only have moist skin.
If you want to find out more about the characteristics of amphibians then you should check out the video below.
What are fish categorized as?
They belong to a phylum called Chordata.
At some point during their life cycle, all Chordata members must have the following five basic traits that separate them from all other species:
- A notochord.
- A tail.
- A dorsal hollow nerve cord.
- An endostyle or thyroid.
- And pharyngeal slits.
Conclusion
Now you know that fish are not classified as mammals because they simply do not contain the characteristics that are required to classify them as mammals.
They, for example, do not possess any hair, don’t have limbs or toes, and are cold-blooded animals instead of warm-blooded animals.