Common symptoms of arthropods
Common symptoms of arthropods
Common symptoms of arthropods
Arthropods
ancient animal. The most reliable data on which to judge the origin of certain groups of animals, provide research resources fossils of organisms or their impressions. From Cambrian sediments known crustaceans, some of them are modern troops from the Silurian period known relatives Xiphosura and even scorpions in the Devonian sediments were found remains nohohvostok. Type arthropods includes 13 classes, among which the most well known: Crustaceans (Crustacea) Merostomovye (Merostomata) Arachnids or arachnids (Arachnida). In crustacean body is divided into head, thorax and abdomen.However, this division has various options. For example, biologists distinguish zhabronohyh, copepods, usonohyh and higher crustaceans.
Merostomovye
very ancient marine animals. Present there are only five species. They semicircular tops and long, sharp tail needle (hence their other name - Xiphosura). In the shell are five pairs of walking legs, followed by the gills.
In arachnids body divided into cephalothorax and abdomen. They have four pairs of legs that grow from the cephalothorax. Instead of the typical insect facet eye to eye built as simple points and record only the movement and the difference in illumination. Spiders live mostly on land. Biologists distinguish scorpions, spiders, mites and hay.
Myriapoda
His nadklas have centipedes (Myriapoda). In these animals several segments merged and formed the head capsule. It connected elongated, divided into segments body. Some centipedes are interconnected segments, each provided with a pair of limbs. In other centipedes segments fused in pairs, every segment marked these sit two pairs of legs.