The body of arthropods consists of segments and is covered with a dense chitinous cuticle, which serves as the outer skeleton. Articulated limbs are movably connected to the body. In the body, three sections are usually distinguished: the head, chest and abdomen. In spiders, the head and thoracic regions have merged to form the cephalothorax. Ticks have a solid body, without visible boundaries between departments. On the head of arthropods are the sense organs and organs for capturing food. On the chest there are motor limbs – legs, and in insects and wings. The abdomen contains most of the internal organs.
Arthropods have special respiratory organs. In aquatic animals, these are gills, in terrestrial animals – trachea or lungs. The circulatory system of arthropods is not closed. From the multi-chambered heart, blood flows through the vessels into the body cavity and circulates between the organs. The digestive organs of arthropods are significantly modified depending on the way of feeding. The excretory organs of many arthropods living on land are excretory tubes – Malpighian vessels.
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