Arachnids are a group of chelicerate arthropods (they lack antennae), characterized by having four pairs of thoracic appendages. They represent a very diverse group; the most common species are spiders, ticks, mites, scorpions, among others. They usually live in warm or tropical regions. Their preferred medium is the ground, where they can move unnoticed among the dry leaves.
Arachnids are mostly carnivorous animals that feed on insects, worms, and even other arachnids. There are species such as mites that are hematophagous ectoparasites, that is, they live on another organism, feeding on its blood or the keratin of the skin. For their part , spiders are experts in applying hunting strategies, such as making spider webs that immobilize insects.
Arachnid anatomy is divided into two regions: the cephalothorax and the abdomen. The appendages are inserted into the cephalothorax. Next to the mouth are a pair of pedipalps and four pairs of legs. They do not have antennae and generally have one or more pairs of simple eyes. Their respiration is aerial, they have tracheas and filotracheas. In relation to their circulatory system, arachnids have two hearts that are located in a kind of tube.
Most arachnids are harmless and even beneficial to humans, and their action allows the destruction of harmful insects. However, there are very dangerous species such as scorpions and spiders called "black widows"; as well as others that are carriers of diseases, such as ticks and mites.
In the case of scorpions, these have small pedipalps and highly developed chelicerae in the form of pincers. At the end of their abdomen they have a stinger that they use to inject poison into their prey; They are of nocturnal habit and generally tend to be under the stones. Its reproduction is through eggs.
The spiders feed only on live prey moving their hunting method is through their chelicerae, which are used to inject poison and kill animals. Their reproduction is also oviparous.
Mites, on the other hand, are arachnids of tiny sizes, with the exception of ticks that are perceptible to the human eye, their body is of different shapes: long, short, round, etc. they may have two, three, or four pairs of legs.
