Nervous system of birds. What is the nervous system of birds different from the nervous system of reptiles?

Birds are the largest group among vertebrates. They are common in all ecosystems of our planet and inhabit even some parts of Antarctica. Which structure has the nervous system and sense organs of birds? What are their features? What is the nervous system of birds different from the nervous system of reptiles?

Class of Birds

Birds are the most diverse and numerous group of vertebrates. In nature, they play an important role, being a link in the food chain. Feathered eat insects, and they, in turn, feed on mammals. In addition, they are important for human economic activities - they are bred for meat, eggs, feathers, fat.

There are more than 10 500 modern bird species and about 20 300 subspecies. In Russia, there are 789 species. The main feature of this class is the presence of wings and feathers, which covers the body of animals. The main mode of travel for many species is flight, although some wings do not perform this function.

The ability to fly affected the external and internal attributes that the Bird class possesses. The nervous system, the digestive and respiratory system differ in structure from the organs of other animals. For example, they have two types of respiration, enhanced metabolism and gas exchange.

Features of the structure of the nervous system of birds

Usually the nervous system consists of nerves located in different parts of the body, as well as from different parts of the brain. All these structures closely interact with each other. They represent a single mechanism that regulates the work of all body systems and is responsible for the reaction to environmental stimuli.

The organs of the nervous system of birds form the central nervous system (spinal cord and brain) and peripheral parts (nerve endings, nerves of the spinal cord and brain). The structure of the brain has common features with vertebrates, although some features significantly distinguish it.

The structure of the nervous system and sense organs of birds is directly related to their life activity. Birds have a good sense of balance and coordination of the movements that they need to fly. Due to this they perfectly maneuver in the air.

Most species feed on moving food. Whether insects, fish, rodents or reptiles, it is important for birds to orientate themselves well in space and to have excellent vision, hearing and quick reaction. The organs responsible for these functions are best developed in birds.

Brain

One hundred years ago it was believed that birds are not capable of complex actions. Ludwig Edinger advanced the theory that their brains are subcortical nodes that are responsible for instincts and simple functions. Later it turned out that the nervous system of birds is very similar to human.

The largest part of the brain is the forebrain. It consists of two hemispheres with a smooth surface, filled with subcortical nuclei. They are responsible for orientation in space, behavior, mating, eating. Hemispheres are connected with a fairly large cerebellum, which regulates the coordination of movements.

The medulla oblongata is part of the brain stem. This department is responsible for vital functions for the bird: blood circulation, breathing, digestion, etc. The middle brain is well developed, it consists of two hillocks that are responsible for processing auditory and visual information.

Birds have a large pituitary gland, but their epiphysis and the intermediate brain are not developed enough. The total number of head nerves is 12 pairs, but the eleventh pair is slightly separated from the tenth.

Spinal cord

The central nervous system of birds also includes the spinal cord. From the brain it is divided conditionally. Inside it is a cavity or central channel. Above, the spinal cord is protected by three membranes - soft, arachnoid and solid, from the central canal they are separated by cerebrospinal fluid.

In the lumbar and humeral divisions, the spinal cord of the birds has small bulges. Here, nerves diverge from him, which connect with the fore and hind limbs. Thus, the pelvic and brachial plexus is formed.

In the lumbar region, the central canal has an expanded rhombic fossa, which is covered by the connective tissue membranes. The branches of the lumbar and brachial plexus of the spinal cord are responsible for the work of the muscles of the corresponding limbs.

Difference from reptiles

Both classes belong to the higher vertebrate animals, and in terms of the structure of the nervous system, birds are closest to reptiles. However, there are significant differences between them. What is the nervous system of birds different from the nervous system of reptiles?

Birds and reptiles have the same parts of the brain. The difference is observed in the sizes of these departments, which is associated with a different mode of animal life. Reptiles have 12 pairs of nerves that depart from the brain, and their spinal cord has thickenings in the lumbar and humeral divisions.

The nervous system of birds is distinguished primarily by the size of the brain, which considerably exceeds the brain of the reptiles. Its mass is 0.05-0.09% (based on body weight) in ratites and 0.2-8% in flying birds. The cerebral cortex of the forebrain in birds is a relic or a rudiment. In reptiles, it is better developed because of the onset of sexual sense of smell.

Birds have no sexual sense of smell, and the sense of smell is very poorly developed, except for species that feed on meat. In both classes, a significant proportion of the forebrain is formed by striped bodies on its bottom. They are responsible for analyzing and responding to incoming information.

Sense organs

The least developed feelings in birds are the sense of smell and taste. Most species hardly distinguish smells, except predators, for example, American vultures. The taste of food is determined by taste buds, located at the base of the tongue and on the palate. There is no special need for them, as the food is basically simply swallowed.

Tactile receptors are in different places. They are represented by the bodies of Grandi, Gerbst or Merkel. In some species they are located near the bases of large feathers on the skin, as well as on the beak in the wax. In owls, for this purpose, there are special feathers on the beak, in waders and ducks, the receptors are in the jaw apparatus, the parrots in the tongue.

The best way for birds is sight and hearing. Their ears are covered with feathers and deprived of auricle. They consist of the inner, middle and rudiments of the outer ear. In sensitivity to sounds, they surpass many mammals. The owls, the salagans, the guaharo have the ability to echolocation. The developed labyrinth of the inner ear provides birds with an excellent sense of balance.

Birds have sharp monocular vision (in owls binocular). Some are able to see at a distance of one kilometer. The eyes have a flattened shape and a wide view. They are inactive, therefore the birds often have to turn their heads. In some species, the angle of view is 360 degrees. The retina reacts even to ultraviolet, and the flexible lens allows you to see even underwater.

Intelligence

During their long history, birds have shown the ability to cope with complex situations, make calculations and show ingenuity. They are able to memorize and reproduce various sounds and phrases of human speech.

For their needs, birds often use objects as tools. For example, with small elastic rods, they can reach insects in the bark of trees. The wood finches use for this purpose spines of cacti, and some have learned to make tools themselves.

Birds quickly adapt to the environment. For example, the tits learned to peck holes in the lids of bottles with milk, and sometimes even remove them. Species that feed on fish, sometimes throw a false bait in the pond to attract prey.

Crows repeatedly throw a nut on the ground, until it breaks. Eagles for the same purpose lift high into the air a turtle, seemingly securely hidden in the shell. Some birds, to break the shell of the prey, throw stones at it.

Conclusion

Birds have a more developed nervous system compared to reptiles. The brain is much larger in size, which allows you to perform more complex tasks, develop complex forms of behavior and adapt to different situations.

The nervous system of birds consists of the head, spinal cord and twelve pairs of nerves. The anterior, middle parts of the brain, as well as the cerebellum, are well developed, which is primarily due to the ability of birds to fly.

They have excellent hearing and sight. They distinguish not only the familiar colors, but ultraviolet, and some have the ability to echolocation. Taste and smell are very poorly developed. The location of tactile receptors is in different parts of the body, depending on the species.