Arachnids: characteristics, types and examples

Arenides are a class (Arachnida) very numerous of invertebrate animals and are included in the edge of The arthropodstogether with insects, crustaceans and miriapods. This class consists of:

• Spiders
• Scorpions
• Mites
• Sea spiders

They are located within the subfilus of the chelitates, which also includes the merostomados and picnogonido. The arachnids are those chelored with greater evolutionary success due, in large part, to its unique survival characteristics and its adaptation to the land environment. These are lonely organisms that are only grouped for reproduction.

Exist More than 100,000 species Known of arachnids and the fossil record seems to indicate that these would have been one of the first animals to live in the terrestrial environment, possibly from the lower devonic period, almost 400 million years ago.

Do not hesitate to take a look at the next Ecology Verb article to know more about what arthropods are: characteristics, classification and examples.

As we have mentioned, the arachnids are part of the arthropods. Therefore, these are the main characteristics of arthropods and that, therefore, they are also present in the arachnids:

• They have a firm and flexible exoskeleton: Composed of proteins and chitina, of which they perform mute periodically.
• They show articulated and specialized appendices.
• They have a Open circulatory system: So blood flows throughout the body, without being contained in blood vessels.

Main characteristics of arachnids

Now we are going to focus on the main characteristics of the arachnids. To begin with, the arachnids present the body differentiated in two tagmas:

• The prosoma: Cephalothorax. This part lacks segmentation and has four pairs of marching legs, a pair of chewers for the capture of dams or defense and a pair of pedipalpos with sensory, locomotive or reproductive function, as well as between 2 and 10 simple eyes or ocellos (simple photoreceptors).
• Opistosome: abdomen in question.

Other characteristics of the arachnids are the following:

• Have jaws: necessary to bite and chew food.
• They present 8 Appendices: Also known as legs.
• They have the head and the thorax fused: forming the combined structure called cephalothorax.
• Are Carnivorous animals: In general, and feed on the bodily fluids of their prey, for which they excrete digestive enzymes about them and, subsequently, absorb them by stomping, a pumping and suction organ.
• They lack Antennas, claws or wings.
• Are cold -blooded animals: So your body temperature depends on the environment. We present other cold blood animals, in this article.
• They have a respiratory system compound By: tracheas or lungs in book for gas exchange, both systems (tracheal and pulmonary) being independent of each other.
• They present a Very concentrated nervous system: except in the case of scorpions. The majority of thoracic and abdominal nodes have merged with the sub-sophagic and are organized in a ring surrounding the esophagus. They lack Deutocerebro.
• They have a arterial circulatory system: With the heart inside the opistosome (although it may be absent, as in the case of mites). In many arachnids, blood has hemocyanine instead of hemoglobin.
• They have a Excretory system specialized in water conservation: They excrete guanine and uric acid through the coxal glands (on the sides of the prosoma) and the malpigio tubes (open in the back of the intestine) or accumulate it in intestinal cells and nephrocytes.
• Are nightclub animals: With the exception of scorpions, which are more active during the day, like some solpogids and spiders.
• They present Courtship behaviors In their reproduction: the scorpions perform a dance from one place to another and back, while intertwining their tails. Spiders reproduce sexually and there is usually intercourse and a variable courtship behavior, which can imply the development of a dance or sound emission.
• Have simple eyes: especially, spiders that are very active usually have very well distributed eyes to have a vision in practically 360º.
• Have simple sensory organs and very specialized: sensilas (chemiorreceptors at the extremes of the appendices), hairs distributed throughout the body (mechanoreceptors), tricobotrios (organs that detect vibrations), liriform organs (sensory fosettes that serve for guidance) and tarsal organs (detect feromones and are found in the distal part of the appendages).

He arachnid group It consists of 10 orders, of which we are going to treat the scorpions (scorpionide order), the spiders (araneae order), the mites (order carei) and the opilions (opilionida order). Thus, these are some of the Types of best -known arachnids:

Spiders

They know about 40,000 species. Prosome and opistosome are separated by a peduncle or pedicel. The different parts of the spider are:

• In the dorsal part They present: The eyes and ventral are distinguished by the quelíberos, where it connects with the poisonous gland, the pedipalpos, the legs and a highly developed sternum.
• In the ventral part From the opistosome are: the epiginium, which is a plaque that covers the genital hole in females, stigmas, which are clefts communicated with the lungs in book, the tracheal hole, which communicates with a system that transports the air to the cells and rows, which are structures through which the silk is poured with which they weave the “spider web”.

So that you can discover more about these animals we recommend you consult these other articles on the importance of spiders and on the violinist spider: characteristics, images and symptoms of their sting.

Scorpions

Of scorpions are known about 2,000 species. In addition to prosoma and opistosoma, they present the Telson or poisonous nail. In the scorpions the prosoma has quelíberos and pedipalpos finished in clamp and the dorsal part is covered by a chitinose plate with keels. On this plate are the eyes, a couple of them medium and three smaller pairs.

• In the ventral part: From the prosoma there are pre-oral and oral appendices, as well as the sternum, a small plate that separates the insertion point of the third pair of marching legs.
• In the dorsal zone: From the mesosome, five external are observed, the genital opercles (they cover the genital hole), the combs (tactile organs) and the stigmas (respiratory holes) and, in the ventral part, the anus. Metasome has the capacity to move vertically and allows the dams to be nailed.

Learn more about them in this other article on difference between scorpion and scorpion.

Mites

In this type of arachnids the own mites and ticks. Of generally small sizes (about 1 mm), there are species up to 3 cm long (such as certain ticks). Approximately, they know each other around 30,000 species.

Your body It lacks divisionsbecause prosoma and opistosome are merged. The region of the head is composed of a series of mouth pieces and is called Gnatosoma or Chapter. Some of the characteristics of these types of arachnids are:

• They present multiple distributed mushrooms For the body surface: they can have sensory function, as well as plates that cover the ventral part.
• His eyes are underdeveloped.
• They can be harmful to the floors and animals: For example, the human being, since they act as vectors of pathogenic microorganisms.

Opilions

Some are known 6,500 species of opiling. They live in humid forests, they are omnivorous animals and, instead of carrying out an external digestion of their prey, fragment their body and, subsequently, suck it to perform intestinal digestion.

THE PROSOME OF OPILIONS There is no segmentation And it is linked to the opistosoma, which has 9 segments, tri-articulated chelicados and some pedipalpos with what. In turn, they have a couple of eyes, as well as marching legs with bases in the form of chewing plates.

Now that we know what is the classification of arachnids and the types that exist, then we will know other examples of arachnids so you can recognize them.

Finally, you can know several examples of arachnids:

• Scorpions: common scorpion (Buthus occititanus) and emperor scorpion (Pandinus Imperator).
• Spiders: Royal turkey spider (Marathus voens) and American black widow (Latrodectus Mactans).
• Mites: Blomia tropicalis and Lepidlyphus destroyer.
• Opilions: Scotolemon Catalonicus and Pachyloides Hades.

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