What Is the Difference Between Fish & Reptiles?

Fish and reptiles have distinct characteristics.

Reptiles and fish share the common features of being cold-blooded and being vertebrates, but that's about where their similarities end. While reptiles and fish seem to be similar, they are more different than they appear and their differences begin with their habitats. Gills, scales, legs, water and land are just a few items that separate these creatures.

The Facts

Fish live in fresh and saltwater habitats.

Fish include the variety of underwater creatures that live in fresh and salt water. They generally have fins on both sides of their bodies, which have a torpedo-like shape. Fish cannot live outside of their water habitat for very long, as their gills do not work with air. Some fish do have organs that operate like lungs but they still live in water. There are a variety of fish, including eels, sharks, puffers and rays.

Reptiles are vertebrates like fish because they have backbones. However, reptiles have dry skin and live quiet well on land. Reptiles include alligators and crocodiles, lizards, snakes, turtles and tortoises.

Identification

Some reptiles, such as snakes, don't have legs.

An easy way to identify fish and reptiles is simply by looking at them. Fish don't have legs and they have gills of varying sizes that provide them the ability to move about underwater.

Reptiles do not have gills and they breathe air like most mammals. Reptiles have scales on their bodies and have very short legs. Many reptiles with legs also have claws on their toes. However, some reptiles, like snakes, don't have legs. Most reptiles will shed their skin as they develop.

Habitat

Some turtles hibernate in colder climates.

One significant difference between fish and reptiles is where each lives. Fish live in water. Some fish live in saltwater, such as tuna, sharks and swordfish. Other fish, such as catfish, trout and bass, live in fresh water.

Reptiles live on land and can live hundreds of miles away from any sources of water. Reptiles living in colder climates will hibernate during winter months.

Reproduction

Fish lay eggs in water.

Fish lay unshelled, undeveloped eggs in water . The eggs must be fertilized by male fish. The young live in the water for a certain amount of time before hatching.

Most reptiles lay amniotic eggs on land; however, some give birth, according to an article posted on Critter Zone. When baby reptiles hatch, they often look like smaller versions of their parents, whereas most baby fish do not.

Misconceptions

There are more species of fish than any other species of animal.

Not all animals living in water are fish. Dolphins, whales and seals are mammals. However, there are more species of fish than all species of mammals, birds, reptiles and amphibians combined, according to the Web site Pet Education.

References

• Smithsonian: Who's A Herp
• Critter Zone: Animal Kingdom Classification
• Pet Education: Fish Facts