Scientific Classification: Spiders form the Araneae order in the Arachnida class. There are 105 families of spiders and 10 missing families. Two subordinates are generally accepted. The Mesothelae subordinate contains some primitive forms.
The suborder Opisthothelae contains the Mygalomorphae subregion, which consists of “straight jaws”, usually large, such as the spider and tarantula, and the infra-order Araneomorphae, whose members have altered and more efficient cheliceras.
It contains the most common and most remarkable forms: the blind weaver, the wolf spider and the spiders. Some cribellate-araneomorphs have the cribellum gland, which helps to produce the silk.
Spider is a common name for 34,000 species of arthropod animals with eight feet used for walking, head extensions with poles and poisons and special reproductive organs on the second part of the male body. They are very often used by the silk it secretes.
Like other arachnid species, spiders are terrestrial, although some species have adapted to life in freshwater, they catch air bubbles under water and carry them after them. Spiders are particularly numerous and are found all over the world. Although most have less than 1cm in length, the largest one has a 9cm body, and the legs can be much longer.
The digestive system of spiders is adapted only for liquid food, because animals generally digest their prey outside the body, and then inject the liquid.
The brain is quite complex. Various parts of it are developed, depending on how they locate their prey: by sight or by touch.
Spiders are generally carnivores and feed only on live food, which they can crush, or can inject a venom. The bite of large spiders can be painful, but most are too small to penetrate through human skin, and only a few species are dangerous to humans.
Among these are the “black widow” and his close relatives, who are not aggressive and bite people just in defense. Bite is painful and is followed by fainting, difficulty in breathing. It is rarely fatal, especially in healthy adults. However, medical care should be provided as quickly as possible.
The structure of the spider body is similar to that of the other arachnids, being divided into an earlier part, called cephalothoracic or prosoma, and a posterior part called the abdomen or opiostom.
The two parts are separated by a thin neck that gives the animal the flexibility to use its own silk. Cephalothocele usually has four pairs of simple eyes, which tend to be larger in spiders that even hunt for those who create complicated patterns.
Each first pair of pliers, or chelicerae, has a corner provided with an opening to release poison from a gland at the end of the clamp. The next two parts of the body are called pedipalp, resembling some legs, but are generally modified to become a kind of antennae.
In the male, the pedipal has a “palpation organ” used for reproduction. On the cephalothorax there are four pairs of feet used for walking. On the abdomen there are modified pliers, used to secrete the silk.
The openings on the abdomen lead to cardiac lungs, called because of the layered structure, or to a tube system (trachea) used to carry the air. In some species, both types of breathing may be encountered.
Spider silk is a fibrillar protein that is secreted as a liquid and forms a polymer that is more stretchable than steel and very elastic. A single spider can create more silk.
Although other invertebrates are silk-secreting, spiders use this ability in most ways. For example, they form yarns that help them find their way and do not let them fall. Small spiders, especially young ones, form parachutes to help them get windy, sometimes hundreds of kilometers.
The male uses silk to transfer the sperm of the female, and it makes silk donuts. Silk is used to build nests and align them. The most familiar, yet most amazing use is in building insect traps, called “canvas.” Once the spoil is caught, the spider rolls it back into silk. The different spider webs provide a remarkable example of the evolution of the insulting behavior.
Painters do not have to learn to make blades but can adapt the technique to special conditions, such as lack of weight in spacecraft. The simplest are irregular and stretched to the surface of the earth. The most advanced are particularly elaborate and oriented to intercept the flying insect trajectory.
Shaping is a complex process that involves a combination of sticky pieces with some non-sticky. Sometimes several spiders form a kind of common canvas, but spiders are generally not sociable. Such spiders are mostly based on the touch.
As predators of insects or small animals, spiders are generally useful to humans, although some feed on pollinating insects like bees. They are a source of prey for other animals like some wasps that paralyze spiders and put eggs on their bodies.
The use of the silk for clothing has not been economically successful, but is used for high precision optical instruments. Though spiders have occupied important places in various mythologies, today they are considered repulsive because of the grotesque appearance and the fact that they are hiding in dark places, but also because of exaggeration of their toxicity.
Spiders have two genders, and eggs must be fertilized. Genital openings of the male and female are on the abdomen, but male copulatory organs are structurally spliced on the pliers. He seals the silk in which he stores the sperm, then moves it to the palpinal organs.
After the sperm has been transferred to the female, it can be kept in her body for a longer period of time. The mating ritual is often complicated. Males use silk to recognize their partner, or signal their proximity by pulling pieces of the female’s canvas.
In spiders with a developed view, the mating ritual is associated with shining colors. The male should avoid being confused with the feed of the female. Males are sometimes much smaller than females. This is noticed when the female stops in one place.
Males mature faster and the sooner they reach a female, the greater the chances of reproduction. Spiders’ eggs are protected in silk donuts. Women can guard or take them with it. In some species, the chicks stay with their mother for a longer period and are carried on her body.