Arthropod type and its anatomical characteristics

The fauna is diverse and diverse. All life on Earth is divided into types. One of them is the type of arthropods. It has about 2 million species and is represented by three classes: arachnids, insects and crustaceans.

Structure

All arthropods, regardless of class, have similarities among themselves. So, they have a symmetrical body, which is divided into several sections - segments. Most often there are three. Of these, the abdomen, head and chest are distinguished. Sometimes the last two segments merge. They form the cephalothorax. The body of arthropods is covered with the hypodermis and chitinous cuticle, which represent something like an external skeleton. There are also several pairs of legs that move away from the segments to the sides. The type of arthropod differs from other invertebrates in that the legs of its representatives consist of several parts, between which there is rubber (elastic protein). Thanks to him, the creature can jump.

Circulatory system

The cavity of the body of animals representing the type of arthropods is a mixsocel. It is formed because of the union of coelomic bags with blastocoel. The fluid in the body cavity is called hemolymph. It mixes with blood and circulates in the organs, between them, as well as in poorly developed vessels. As for the circulatory system, it is not closed. Arthropods have a heart. It is represented by a spinal blood vessel, which has acquired a certain shape. Through the lateral apertures, the so-called ostia, which have valves, the hemolymph enters the heart.

Digestive system

The digestive system of arthropods is represented by the posterior, anterior and middle sections. The special tube is divided into sectors. Among them there is a pharynx, stomach, esophagus. In addition, there is a hepatic outgrowth through which enzymes are released. Oral apparatus of arthropods is very complicated.

Respiratory system

Depending on where the creature that enters the arthropod type lives, its respiratory system can look like lungs, gills and trachea. But they are in an embryonic state. Pulmonary sacs (lungs) in this case are the outgrowths of the body wall, which are leaf-shaped and directed into the interior of the body cavity. They connect with the respiratory gaps. Tracheas are formed by numerous branching ducts, which inside have chitin rings. Gas exchange in such animals is due to hemolymph, which delivers oxygen to all tissues.

Nervous system

The central nervous system of arthropods is formed by the brain and the nervous chain. It is located in the peritoneum. The chain has a combination of nerve nodes in the abdominal, head and thoracic parts, so that animals of this type have well-developed sense organs.

Other systems

As for the excretory system, it is represented by malpighian vessels and metanephridia. Animals such as arthropods are of opposite sex, with strongly pronounced dimorphism. The muscular system is also present in these animals and is represented by a striated tissue.