What is the Difference Between Fish and Amphibians?

Fish and amphibians are two distinct groups of vertebrates that share some similarities but also have key differences. Here are the main differences between fish and amphibians:

1. Habitat: Fish are entirely aquatic, while amphibians are not entirely aquatic, as most of their larval stages live in water, but they move to land as adults.
2. Skin: Fish have scales on their skin, while amphibians lack scales and have smooth or rough skin with glands that keep it moist.
3. Heart: Fish have a two-chambered heart, while amphibians have a three-chambered heart, consisting of two auricles and one ventricle.
4. Respiration: Fish mainly breathe through gills, except for lungfishes, while amphibians have lungs for air breathing, although their skin, oral cavity, and gills may also be functional for gas exchange depending on the environment.
5. Number of Species: There are more than 32,000 species of fish, while there are around 6,500 extant species of amphibians.
6. Evolution: Fish evolved before 500 million years ago, while amphibians evolved from fish around 400 million years ago.

Despite these differences, both fish and amphibians are vertebrates and ectotherms, meaning they have backbones and rely on external sources of heat to regulate their body temperature. Additionally, both groups have gills and fins for at least part of their lives, and they lay eggs with soft shells that need to stay in or around water to avoid drying out.

Comparative Table: Fish vs Amphibians

Fish and amphibians are two distinct groups of aquatic animals with different characteristics. Here is a table summarizing the main differences between them:

Fish are aquatic animals with gills that extract oxygen from water, while amphibians are cold-blooded animals that are capable of living both on land and in water. Fish can be found in both freshwater and saltwater environments, but amphibians are more commonly found in freshwater environments.