Are fishes part of the reptilian class? But are they? What makes the fishes different from the reptiles, even if they both have scaly skin and are both cold-blooded animals. They both belong to the Phylum Chordata class.
Fish vs Reptile
The main difference between Fish and Reptiles is that fishes breathe through gills while reptiles do not have gills. They respire through the lungs itself. Their ribs can expand and contract which allows their lungs to have greater capacity than amphibians.
Fish belongs are the largest existing vertebrates species. They belong to the Gnathostomata class. This is a subphylum group and a superclass of Chordata. They are all vertebrate species that have a structure jaw. Some common examples of fishes are clownfish, sharks, etc. They are the species of the animal kingdom that habitat in water.
Reptiles belong to the class known as Reptilian. This class includes a variety are species such as turtles, snakes, lizards, etc. These animals are categorized under the Reptilian class because of their characteristic features such as cold-blooded, dry skin. They are commonly also known as the cold-blooded vertebrates that have epidermal glands.
Comparison Table Between Fish and Reptile
| Parameters of Comparison | Fish | Reptile |
|---|---|---|
| Excretion of waste | Excretion takes place through the gills | Have a defined excretory system with well-functioning kidneys. |
| Limbs | Their limbs are modified as fins | Some have proper forelimbs and hind limbs while species like snakes do not have them |
| Skin | Usually have bony and skinny scales | Rough and dry skin without glands |
| Respiration | Through gills and have 6-7 gill pouches | Through lungs |
| Habitat | Only water, mainly fresh-water and rivers | Both land and water |
What is Fish?
Fishes are the species that belong to the Phylum Chordata class and the vertebrate species. They are found in freshwaters and rivers and have gills and gill pouches for breathing. They mostly develop and fertilize eggs outside their bodies.
Fishes are further categorized into three: Agnatha, Chondrichthyes, Osteichthyes. They are categorised based on the difference in the fish’s structure.
The agnatha fishes do not have a jaw. The ancient species were said to have bony and scaly skin but nowadays this feature is absent. They do not have a stomach in their digestive system and the paired fins are also absent in them.
Chondrichthyes are also known as cartilaginous fish. They mostly consist of the predatory and muse eating fishes like sharks.
Osteichthyes have a defined jaw and paired fins, unlike agnatha fishes. They have mucus glands on their skin and these species constitute almost 3000 varieties of fish. These fishes also a bony skeleton and have numerous vertebrates.
The fishes use their gills itself as their excretory system as well. The nitrogenous waste is diffused into the water through the gills.
What is Reptile?
According to statistics, there are almost 6000 species of reptiles across the globe. These cold-blooded animals are usually terrestrial and are also found in warmer places around the globe.
Their features are dry and rough skin, that have epidermis glands. They also have modified limbs for crawling, except in the case of snakes.
Unlike fishes, reptiles have three-chambered hearts: two auricles and a partly divided ventricle. Reptiles, even though some live-in water do not breathe through gills. They have lungs and their ribs are capable of expanding. This provides greater capacity than amphibians.
Reptiles are mostly oviparous (lays eggs). They all form the embryonic membrane on the eggs. Reptiles are also capable of laying eggs on land because they are amniotic. Some say that the different types of reptiles came in due to the evolution of fishes.
Reptiles have two well-functioning kidneys but they cannot produce urine.
Conclusion
Thus, we can remove the common misconception that reptiles and fishes belong to the same class in the animal kingdom and have many differences between them.
Fishes are found mainly in freshwater or river. They are one of the largest numbers of vertebrate species to still exist in the world. Based on their structure they can be further divided into three categories. Common examples of fishes include clownfish, sharks, electric eel, etc.
Reptiles are mostly terrestrial animals but can be found to have a habitat in fresh-water as well. But they do not have gills, unlike fishes. They have lungs like most amphibians, but these lungs have greater capacity than amphibians. Common examples of reptiles include snakes, lizards, turtles, etc.
The difference that marks between fishes and reptiles is the ability of reptiles to exist on both land and water whereas fishes are unable to survive out of water. Their respiratory system is designed to only function when in water. Reptiles have two functional lungs, as present in amphibians and mammals.
References
- https://www.sciencedirect.com/science/article/pii/S0009254101004247
- https://eje.bioscientifica.com/view/journals/eje/100/2/acta_100_2_016.xml