Animal senses: a brief description

Any living organism is an ideal system, and if the circulatory, nervous and other organ systems allow us to exist, then the senses are exactly what the body cognizes and perceives the external environment. In this case, each class of animal organisms has its own characteristics.

Organs of the senses of fish

Representatives of this class of animals have fairly developed eyes, which consist of the retina, the lens and the cornea. The principal difference between these organs is that when perceiving an image, the lens does not change the curvature, as in the other vertebrates, it simply moves relative to the cornea, thereby focusing the eye.

There are fish and organs of hearing, which are three semicircular, mutually perpendicular canals. Some representatives also have a so-called Weber organ, which connects the cavity of the inner ear with the swim bladder, which in this case acts as a resonator of sound. Receptors that perceive the taste and smell, can be located not only in the mouth and nostrils, but also scattered throughout the body.

Another interesting organ is the lateral line, which is a set of channels associated with nerve fibers. The lateral line is especially developed in those fish that do not have eyes - it is thanks to it that they can perceive the external world and maintain balance.

It's no secret that some fish can react to electric fields and even generate electrical impulses with the help of special cells and nerve fibers.

The sense organs of amphibians

The sense organs of representatives of this class are already more adapted to existence in the air. For example, their eyes already have eyelids, as well as a blinking membrane that performs moisturizing and protective functions. The lens can change its size depending on the lighting.

In addition, amphibians have olfactory bags that open outward with nostrils. An animal can only smell odors in the air. As for the hearing organs, the amphibians are already forming the middle ear and the tympanic membrane, as well as a small bone called stapes.

All mechanical receptors are located in the skin tissues. The primitive water amphibians, as well as tadpoles, still have a lateral line.

Organs of the senses of reptiles

In the representatives of this class, the senses are already more developed and adapted in life in the air. Very important for these animals are the eyes that are more formed than in amphibians - there are developed muscles that attach to the lens and can change its curvature in order to focus the image. In addition, reptiles have real tear glands, the secret of which protects the animal's eyes from drying out. There are mobile eyelids.

Such animals have choana (internal nostrils), which are located closer to the pharynx, which greatly facilitates breathing during meals. It is proved that reptiles are much more sensitive to smells than representatives of an amphibian class.

The organs of taste are represented by specific structures - taste buds that are located in the pharynx. And between the eyes and nose is located the so-called facial fossa, which allows you to respond to temperature changes. For example, in some snakes, this organ allows you to quickly find food.

Hearing organs are not very well formed and resemble an amphibian hearing aid. Reptiles have a middle and inner ear with a tympanic membrane, as well as a stapes - a small bone that transmits vibrations to the tympanic membrane. Rumor in the life of these animals is not particularly important. For example, in snakes it is practically not developed.

Apparently, the sense organs gradually changed in the course of evolution, adapting to survival under certain conditions and becoming more complex and functional.