Features of the similarities and differences of amphibians and fish compare the signs

About 400 million years ago, some fish left the usual habitat, reaching land. This led to significant changes in the structure of the body, because the aquatic environment is much denser than the air and pushing forces in it stronger. An important difference is that in the air some metabolic processes in the body can only occur in solutions.

Differences of amphibians from fish

The first important difference from fish is the presence of amphibians of two circles of blood circulation. The circulatory system has changed as a result of the fact that amphibians began to breathe atmospheric air. So, a small circle passes only venous blood, and a large one only arterial. For ease of operation of such a system, the heart began to be divided into 1 ventricle and 2 atrium.

The small circle originates in the ventricle, then goes to the vessels of the lungs and ends its path in the left atrium. The large circle also also begins in the ventricle, then passes through the vessels of the brain, and then returns to the right atrium. It turns out that in the ventricle arterial blood is mixed with the venous. This mixture captures the vessels of all other organs. In contrast to such a logical system, fish has only a large circle of circulation, according to which venous blood circulates. And the heart of the water inhabitants is twochamber.

Pisces and amphibians have a completely different body shape. For water inhabitants, it is often a torpedoshaped, pressed on the sides. For the most part, it consists of soft fabrics. This is necessary in order to be able to bend, floating away from predators. In amphibians, the body is as if pressed from above, such a structure is due to the power of attraction of the Earth. These representatives of the fauna have many specialized muscles that provide good flexion and extension of the limbs. Their limbs belts are very tightly attached to the spine. All this helps the amphibians constantly hold the weight of the whole body over land.

The amphibians have a neck that allows you to leave the head almost motionless when examining the surface. In these representatives of the fauna, the spine is more complicated than that of fish, it consists of a cervical, trunk, sacral and tail.

Another difference due to adaptation is the wet and pierced through capillaries the skin of amphibians, which can “breathe” absorb oxygen, and the skin of water inhabitants is covered with impassable scales.

The next difference is that the nasal cavity of amphibians is associated with the mouth, when the fish out of the nasal cavity has one out. Penetrating over the oral cavity of amphibians, the air becomes wet.

The structure of the auricle has also changed. The amphibian has a drum membrane, very small bones that transmit sound vibrations of the inner ear so the animals adapted to the fact that the sound spreads much worse in the air.


The main similarity is that both fish and amphibians belong to the type of chordal. All representatives of this type are coldblooded, that is, the temperature of the external environment greatly affects the temperature of their bodies. The bodies of representatives of both types have bilateral symmetry. Both fish and amphibians have touch and smell.

The type of reproduction is no less important: both are propagated by the throwing of caviar. Naturally, there are a number of viviparous fish and amphibians, but this is rather an exception than the rule.

Similarities and differences table

Signs Fish Earthovod
Habitat Water environment Ground-water environment
Symmetry of the body Bilateral Bilateral
Body parts Head, body, tail, fins Head, body, limbs
The organs of movement Tail and fins 2 pairs of limbs
Body cover Leather, scales, mucus secreted by skin glands Skin, mucus secreted by skin glands
Body skeleton Skull, spine, skeleton of fins, ribs, cervical vertebra Skull, spine, skeleton of limbs, skeleton of the limbs, there is one cervical vertebra
Respiratory system Gills Light, skin breathing
The structure of the heart Atrium and ventricle 2 atrium and ventricle
Circulation One circle of blood circulation Two circles of blood circulation
Brain 5 parts of the brain 5 parts of the brain, the cerebellum is less developed
Senses Vision (eyes), smell (nostrils), touch, taste, side line, hearing Vision, smell, touch, taste, hearing (drum membrane)
Reproductive organs Seven and ovaries Seven and ovaries
Fertilization External (for most) External
Development Without transformation From transformation (tadpoles)
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