Insects are so small and have brains?

I don't think there is one. I won't know until I check. There was one.

In addition to the brain, the nervous system of insects is mainly composed of a series of ventral nerve cords. So insects are similar to annelids and belong to the type of abdominal nerve cords. The nervous system of insects consists of central nervous system, sympathetic nervous system and peripheral nervous system. The central nervous system is the control center of insect nerve impulse and endocrine. The sympathetic nervous system mainly includes the oral sympathetic nerve that controls the digestive tract and the intermediate nerve that controls the valves and blood vessels in the back. Peripheral nervous system is a neural network composed of nerve fibers of sensory neurons and motor neurons, which is mainly distributed on the body surface of mollusk larvae.

First, the central nervous system

The centralnervous system (CNS) includes the brain and ventral nerve cords located in the front and back of the digestive tract, which are connected by the perineal nerve cords, and are the control centers of nerve impulses and endocrine.

(1) The brain of a brain worm is composed of three pairs of ganglia in the head, located in the skull above the throat, which is the most complicated part of the nervous system. Although the brains of modern insects have many changes in appearance, they are all composed of midbrain, midbrain and hindbrain. The back of the brain is connected with the lower esophageal ganglion below the throat through the peripharyngeal nerve cord.

1. The forebrain is located at the forefront of the brain, accounting for more than half of the brain. On both sides, it is an enlarged and prominent optic papilla with a slender monocular stalk on the front and back. The nerve in the forebrain mainly leads to compound eye and monocular eye, which is the visual center. The internal structure of forebrain is complex, including spherical cell group, brain body (also known as nerve fiber body) and nerve connective tissue.

The brain body consists of dense nerve fiber groups and nerve fiber balls (small balls where nerve endings gather). There are four kinds of * *, namely pons, centrosomes, mushrooms and ventral bodies.

(1) The pons are mostly horseshoe-shaped and located in the center of the back of the forebrain. Nerve fibers from many parts of the brain all enter the pons, so it is the contact center. The dorsal side of the pons of lower insects is connected with a pair of spherical cell groups respectively.

(2) The central area is oval under the pons, which is the intersection of nerve endings of various parts of the brain and an important contact center.

(3) Mushrooms are located on both sides of the pons, one on the left and one on the right, and are shaped like mushrooms. Mushroom is the most important and complicated coordination and contact center in insect brain. Its size and complexity are related to the complexity of insect behavior, and it is considered as a sign of insect intelligence.

(4) The medulla oblongata is slightly spherical, one in the front, back, left and right of the brain, connected by transverse nerve cords, and connected with the nerve centers such as the brain body, optic lobe and antenna through nerve fibers, which is also the contact center.

The forebrain is the control and coordination center of all activities, growth and development of insects. There are groups of nerve secretory cells in the middle of the brain, and their nerve axons extend backward to the heart body, which have the functions of secreting, storing and releasing brain hormones.

2. The midbrain is located behind the forebrain and consists of two enlarged midbrain lobes. There is a medulla on each side of the midbrain, which is the nerve center of the antenna, and there are many connecting nerves connected with the medulla of the chest. The two medulla oblongata are connected by nerve cords, and the sensory nerve fibers of the antenna form many nerve fiber balls around them.

3. The posterior part of the brain is located in the posterior part of the midbrain and is divided into two lobes, which are usually underdeveloped. There is a medulla oblongata in the posterior lobe, and its nerves lead to the frontal ganglion and the upper lip. The medullary body of the posterior brain is in the posterior lobe, but the nerve connecting the two medullary bodies is outside the brain and bypasses the pharynx, so it is called the peripharyngeal nerve ring.

(2) The ventral nerve cord is located in the lower part of the digestive tract and consists of the hypopharyngeal ganglion, the somatic ganglion and the nerve cord connecting the ganglia longitudinally.

1. The hypopharyngeal ganglion, also known as the inferior esophageal ganglion, is located under the throat in the head shell. It is the 1 compound ganglion in the abdominal nerve cord, which is formed by merging three pairs of ganglia that constitute the last three segments of the head (maxillary segment, mandibular segment and lower lip segment). Nerves from the hypopharyngeal ganglion lead to the maxilla, mandible, lower lip, tongue, salivary duct and neck muscles. Its main function is to control and coordinate the movement of mouthparts, so it is the nerve center of mouthparts. These nerves all contain sensory and motor nerve fibers.

2. Somatic ganglion insects can have at most 1 1 opposite ganglia, that is, 3 pairs of chests and 8 pairs of bellies. Three pairs of ganglia in the chest are located in the anterior chest, middle chest and posterior chest respectively. The emitted nerves reach the feet, wings and chest wall. Eight pairs of abdominal ganglia are located in the abdominal segment of 1-8, and the last pair is a compound ganglion, which is formed by merging at least three pairs of abdominal ganglia in the abdominal segment of 8- 10. The nerves from the abdominal ganglion lead to the body wall, caudate beard and various reproductive organs respectively. Ganglion has relative "autonomy" to its body segments and becomes the nerve center of each body segment, while the last pair of ganglia is the nerve center that controls reproductive organs and hindgut movements.

With the evolution of insects, ventral nerve cords often move forward and concentrate along the longitudinal axis, and different insects have different degrees of healing. For example, the number of ganglia in primitive symptoma is typical, the posterior thoracic ganglion of locust is formed by merging the posterior thoracic ganglion and the first three abdominal segments, while the thoracic and abdominal ganglia of housefly are all merged into one thoracic ganglion. With the improvement of ganglion healing, the comprehensive ability of insect nerves has also been strengthened.

Second, the sympathetic nervous system

The sympathetic nervous system of insects mainly controls the activities of internal organs, and consists of oral nervous system, intermediate nerve and the last compound ganglion of abdomen.

(1) Oral nervous system The oral nervous system generally includes a frontal ganglion, 1-2 posterior ganglia and 1-2 crop ganglia and their nerve branches. The frontal ganglion is located in front of the brain and behind the throat. It is connected to the back of the brain by two frontal nerve cords. The retrograde nerve enters the dorsal ganglion and sends out the nerve to the bottom of the lip and the upper lip, which mainly controls the action of the mouthparts during feeding. Posterior ganglion and crop ganglion control the movement of digestive tract. The posterior ganglion has nerves connected with the forebrain, frontal ganglion, lateral pharyngeal body or lateral cardiac body, esophagus, crop and the front end of midgut, and some of them are also connected with the upper collar muscle and salivary gland duct, which is the activity control center of the foregut, midgut and dorsal blood vessels, and is also related to the growth, development, peeling and metamorphosis of insects.

(2) The nerves in the intermediate nerve generally exist in the larvae and larvae of many insects, and control the activities of valves and dorsal blood vessels. The intermediate nerve is located between the two nerve cords of the two ganglia before and after the abdominal nerve cord. It contains two fine sensory nerve fibers and two thick motor nerve fibers. It originates from the anterior ganglion and extends backward to the middle. Often send 1 contralateral branch to nearby trachea, valve and its occluder. Therefore, the control center of each insect's throttle is located in the anterior ganglion.

(3) The lateral nerve emanating from the last compound ganglion in the abdomen leads to the hindgut, reproductive organs, valves and caudate whiskers, and controls the activities of the hindgut and reproductive organs, so it also has the function of sympathetic nerve.

Third, the peripheral nervous system

The peripheral nervous system includes all motor and sensory nerve fibers and their endings emitted by ganglia, thus forming a dense neural network. The peripheral nervous system of insects is underdeveloped and mainly distributed on the body surface of mollusks. Its function is to quickly transmit the stimuli felt by receptors and nerve endings to the central nervous system, and then the motor nerves send appropriate instructions through information conversion, so that the effector can make corresponding behavioral responses.