Exploring Our World

Similarities and Differences: Fish and Amphibians

Key Changes needed:

1. The development of a skeleton, gills, a swim bladder, and jaws would be key adaptations needed to allow vertebrates to diversify in the oceans.

2. Developing legs, lungs, and a 3-chambered heart would be needed to allow fish to transitionally change into amphibians.

Fish and amphibians are similar in that they both are vertebrates, are cold-blooded, and both hatch from eggs.

However, to get a better understanding of the unique natures of both fish and amphibians, let’s consider how they differ from one another.

1. Body Coverings

Fish are covered in scales. Amphibians have no scales, but moist skin.

2. Respiration

Fish breath mainly through its gills, except for lungfishes. Amphibians breath mainly through lungs. Amphibians have permeable skin, which allows gas and molecules to pass through, but fish do not.

3. Metamorphosis

Amphibians undergo metamorphosis as they grow from young to adult, but fish do not undergo this radical change.

4. Eye Coverings

Amphibians have eyelids, but fish do not.

5. Hearing

Amphibians have ears, but fish do not. Limbless amphibians tunneling in wet and warm soil of the tropics have “seismic” hearing and perceive vibration of the ground by the lower jaw; the sound is transmitted to the inner ear by the skull bones. It is the same with some tailed amphibians. Looking closely at a frog, one can spot behind the eyes, on the sides of the head, small circles covered with membrane. This membrane is the eardrum.

Fish have ear parts inside their heads. They pick up sounds in the water through their bodies and in their internal ear, according to the National Wildlife Federation. Most fish also have sensitive receptors that form the lateral line system, which detects gentle currents and vibrations, and senses the motion of nearby fish and prey.

6. Habitat

Fish live in the water; amphibians may live in water or land.

7. Modes of Travel

Fish propel themselves through water with fins or float along underwater currents and do not have limbs. Amphibians do have limbs and can run, jump, climb or swim both on land and in water.

Two Worldview Interpretations:

Undirected Process Formation

Life forms share common traits and body parts with other life forms because they had a common ancestor.

Directed Purpose Formation

Life forms share common traits and body parts with other life forms because of similar purpose and design.