Within the Animalia kingdom, there is a great biodiversity. For example, some very interesting and that may be strange to us are a large group of arthropods with great evolutionary success in the terrestrial environment, although they also present specimens that inhabit aquatic environments, both marine and freshwater: arachnids.
In this Green Ecologist article we tell you all about the Arachnids: characteristics, types and examples. So, if you want to know more about this group of animals, stay with us and discover various details and photos.
Arachnids they are a classArachnida) very numerous of invertebrate animals and are included in the phylum of arthropods, along with insects, crustaceans and myriapods. This class is made up of spiders, scorpions, mites and sea spiders. They are found within the chelicerates subphylum, which also includes merostomes and pycnogonids. Arachnids are the most evolutionarily successful chelicerates, due in large part to their unique survival characteristics and their adaptation to the terrestrial environment. They are solitary organisms that only group together for reproduction. exist more than 100,000 species known arachnids and the fossil record seems to indicate that these would have been among the first animals to live in the terrestrial environment, possibly from the Lower Devonian period, almost 400 million years ago. Arachnids present the body differentiated into two tagmas: the prosoma (cephalothorax) and the opistosoma (abdomen). The prosoma lacks segmentation and has four pairs of walking legs, a pair of chelicerae for prey capture or defense, and a pair of pedipalps with sensory, locomotor, or reproductive function, as well as between 2 and 10 simple eyes or ocelli ( simple photoreceptors).
In addition to the above, these are the main arthropod characteristics and that, therefore, are also present in arachnids:
The arachnid group It is made up of 10 orders, of which we are going to deal with scorpions (order Scorpionida), spiders (order Araneae), mites (order Acari) and opiliones (order Opilionida). So, these are some of the most known types of arachnids:
About 40,000 species are known. The prosoma and opistosoma are separated by a peduncle or pedicel. In the dorsal part they present the eyes and in the ventral part the chelicerae are distinguished (where it connects with the venomous gland), the pedipalps, the legs and a highly developed sternum. In the ventral part of the opistosoma are the epiginium (plate that covers the genital orifice in females), the stigmata (slits communicating with the lungs in the book), the tracheal opening (communicating with a system that transports air to the cells) and the rows (structures through which the silk with which the "spider web" is woven) is poured.
So that you can discover more about these animals, we recommend you consult these other articles on The importance of spiders and on the Fiddler Spider: characteristics, images and symptoms of its bite.
Some 2,000 species are known. In addition to the prosoma and the opistosoma, they present the telson or poisonous nail. The prosoma has chelicerae and pedipalps ending in pincers and the dorsal part is covered by a chitinous plate with keels. On this plate are the eyes (one medium pair and three smaller pairs). In the ventral part of the prosoma are pre-oral and oral appendages, as well as the sternum, a small plate that separates the insertion point of the third pair of marching legs. In the dorsal area of the mesosome there are five sternums, the genital glands (covering the genital orifice), the combs (tactile organs) and the stigmata (respiratory orifices) and, in the ventral part, the anus. The metasoma has the ability to move vertically and allows prey to be nailed with the stinger.
Learn more about them in this other article on Difference between scorpion and scorpion.
This group includes the mites and ticks themselves. Generally small in size (around 1 mm), although there are species up to 3 cm in length (such as certain ticks). Approximately, about 30,000 species are known. His body lacks divisions, as the prosome and opisthosome are fused. The head region is made up of a series of mouthparts and is called a gnatosome or chapter. They present multiple mushrooms distributed over the body surface that can have a sensory function, as well as plates that cover the ventral part. His eyes are underdeveloped. Mites can be harmful to plants and animals (for example, humans), acting as vectors for pathogenic microorganisms.
Some 6,500 species of opilion are known. They live in humid forests, they are omnivores and, instead of carrying out an external digestion of their prey, they fragment their body and, later, they suck it for intestinal digestion. The opilion prosome does not present segmentation and is attached to the opistosome, which has 9 segments, tri-jointed chelicerae and pedipalps with chelas. In turn, they present a pair of eyes, as well as marching legs with bases in the form of chewing plates.
Finally, here you can see several examples of arachnids:
If you want to read more articles similar to Arachnids: characteristics, types and examples, we recommend that you enter our Biodiversity category.