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Information about the spiders

An Introduction to the Spider

Spiders have a body divided into two parts instead of three compared to insects, and eight legs instead of six, and thus they do not follow insects by classification, and the spiders are characterized by the great color diversity, and this helps to confine them to specific families, some of them have dark colored bodies spread by bright spots, Such as: the tropical gas spider, and there is another family that has brown or black bellies with lighter colors, such as wolf spiders, while the trapdoor spider has a large head whose color usually differs from the color of their stomachs, and it should be noted that the length of the spider's body ranges between 0.5 mm to 90 Approximately mm.

Scientific classification of the spider

The main classification

There are many types of arachnids spread around the world, which scientifically belong to multiple genera that fall under various families belonging to the order Tarantula (scientific name: Araneae), which belongs to the class Arachnids (scientific name: Arachnida) within the class above the class of true antlers (scientific name) : Euchelicerata), which falls under the phylum Craniasis (scientific name: Chelicerata) of the division of arthropods (scientific name: Arthropoda) within the higher phylum Osteophytes (scientific name: Ecdysozoa), which falls under the lower kingdom Proto-stomata (scientific name: Protostomia) under Awelem is bilateria (scientific name: Bilateria) within the animal kingdom.

Classification of families

The number of spiders known around the world reaches more than 46,700 species, classified within nearly 110 families, where spiders are divided into three main orders, namely:

Jaw forceps spiders: Jaw forceps spiders (scientific name: Labidognatha) are distinguished by the presence of foot tentacles located behind specialized front appendages called hooks under a horn or bone shield, and they also contain a distinct respiratory system from the clerical lungs in addition to the bronchi that may act as a respiratory system Instead, as for the heart, it contains three openings and sometimes two, and a double series of divided nerve ganglia, as several families fall under this arrangement, including:

Family of jumping spiders (scientific name: Salticidae).

Family of levae (scientific name: Linyphiidae).

A family of spiders (scientific name: Araneidae).

Family of wolf spiders (scientific name: Lycosidae).

Family of homophones (scientific name: Theridiidae).

Tarantula spiders: jaw spiders or tarantulas (scientific name: Orthognatha) live in warm climates, and when the respiratory system is addressed in this suborder, it is represented by two pairs of the epigastric lung, and the heart often contains four small openings and a double chain of nerve ganglia. The following families descend under this order: (Theraphosidae), (Dipluridae), (Ctenizidae), (Hexathelidae), (Atypidae).

Segmented spiders: It contains one family called (Liphistiidae) under which about 100 species of spiders are included, they are found in Japan to the southeast of Asia, and segmented or segmented spiders (scientific name: Mesothelae) can be distinguished in this order by the segmented abdomen from 7 to 18 Part, and 8 spindles of silk in the middle of the abdomen, and spiders in the frontal region of the prosoma have 18 knots separated from each other more than other arrangements, and the heart contains 5 pairs of small openings, in addition to two pairs of the clerical lung.

The body composition of the spider

The body of the spider is divided into only two parts, namely: the prosoma (in English: Cephalothorax) or the head - the chest, and the abdomen (in English: Abdomen), and there is a narrow knot in the middle that connects the two areas together called the leg (in English: Pedicel), and the parts come in detail:

Prosoma

The upper and lower parts of the prosoma are covered with protective structures; The upper side is covered by the horny shield (in English: carapace), while the lower side is covered by the sternum (in English: the sternum) in addition to the lower appendages called the lip (in English: labium), [6] and the prosoma consists of a number of external organs:

Eye: The spider moves and searches for its prey by relying on touch, vibration and taste more than it relies on vision, but few of them have good eyesight that they use for building, hunting, and wandering, in addition to identifying their mates and predators. Some types of spiders have 8 eyes and others have six or The lowest, best spiders to see are: the jumping spider, the long legged spider, and the wolf spider.

Fovea: The pectoral muscles are internally connected to a point called the fovea, located in the middle of the spine.

The mouth region: This region consists of two jaws that contain fangs, hooks, or hooks called chelicerae, in addition to an upper plate (The labrum) and a lower plate (in English: The labium) that form the upper and lower part of the mouth, and it also contains On a row to chop food in the upper jaw.

Foot tentacles: The spider is able to sense, touch, and taste, in addition to mating with pedipalps in males.

Feet: The spider has four pairs of feet, some of which contain two claws, such as: jumping spiders, where these spiders can stand on smooth and sloping surfaces due to the presence of dense tufts of hair that improve the process of adhesion, while others contain three claws; As a net weaver, spiders also have a number of sensory organs on their legs, such as: the foot tentacles and hair, in addition to small holes in most parts of their body, so that they can taste, smell odors, and feel vibrations. The prosoma also includes the following internal organs:

Muscles: where the limbs and jaws move with the help of muscles.

Cerebral ganglia: Ganglia are made up of a group of nerve tissues.

Venom glands: Spiders kill their prey with the toxin produced by the venom glands.

Muscular stomach: Liquid food reaches the esophagus, pharynx, and intestine by being pumped by the muscular stomach or stomach muscles.

Belly

The abdomen of the spider expands when feeding and developing eggs with the help of the thin and flexible skin that covers it, and when spinning silk and mating, the abdomen moves with the help of the septum that separates it from the prosoma, and for the external organs that make up the abdomen:

The book lung cover: The book lung covers the sensitive organs inside the spider.

Genital orifice: The eggs or sperms reach the reproductive system, which is located in front of the clerical lung pair, after they are released from the genital orifice, and there is another opening called the orifice or the external genital organelles (in English: epigynum) in the spiders Ritelloid shape.

Spinners: Spinners have 4 to 6 spinnerets to produce silk.

As for the internal organs in the abdomen, they are:

Lung lung: Tarantula spiders have two pairs of book lungs, in which the exchange of gases between air and blood occurs after entering it through small openings covered with a layer of very thin skin and linked to cavities that end with book-like pages attached to pillars that prevent them from sticking together. Some small spiders exchange gases across a thin layer of skin. They do not have respiratory organs due to their presence in moist and sheltered places.

Silk glands Silk consists of a liquid protein that is produced by the silk glands.

Heart: The heart is located in the center of the spider's body, where blood is pumped to parts of the body through vessels or cavities and then gradually returned to it, and the circulatory system is open to it.

Hind intestine: Food is absorbed in the hind-gut, and it contains a sac of secretory organelles called Malphigian tubules, which play the role of the kidneys in the spider.

Skin

The body of the spider consists of internal and external organs; Such as the skin, the muscles, the respiratory system, and the digestive system, in addition to the genitals, and the skin, skin, or a solid external structure is characterized by that it is composed of several layers of protein and chitin that cover the body of the spider from the outside, and its function is to provide points of connection or contact with the muscles, in addition to regulating pressure Blood, as it contains hair and nerve appendages that represent the spider's senses, and lines the front and back intestine, trachea, and the sperm storage system in females, and the skin reduces water loss by containing a thin layer of wax.

Spiders fix their muscles on a semi-rigid hydrostatic structure that surrounds the body of the spider from the inside consisting of cavities filled with fluid, and the fluid pressure acts as a stabilizer for the muscles around it, to maintain the body’s shape and function, so blood pressure is affected by the change in heartbeat, contraction and relaxation of the muscles.

The life cycle of a spider

The life cycle of a spider begins from the reproductive process by placing approximately a thousand fertilized eggs in a silk bag after mating. Male spiders put sperm into a web of their own to pull them to the foot tentacles to be inserted into the genital openings of the female that stores them inside to choose sperm capable and appropriate for fertilization Eggs, [10] and the spider's life cycle goes through three stages:

The embryonic stage (eggs): This stage occurs after mating, so that the eggs are kept in a strong silky bag to protect it, and here the way some spiders care for and guard the eggs differs, for example: the mother spider carries the bag with her until they hatch, such as: the wolf spider, and some carry it for ten days on They appear, and for some others, the eggs are left in a safe place until they hatch, and this usually takes a few weeks.

Pre-growth stage: This stage begins after the eggs hatch into small spiderlings that move away from each other by walking, bulging or ballooning, which enables them to travel short distances and sometimes long, by weaving silk threads It releases it from its spindle to blow with the wind and move from one place to another, and with the passage of time the size of the small spiders increases through the process of moulting, as they replace their external structure several times and get rid of it, so the number of moults that occur ranges between 5 to 10 until they reach the stage of maturity.

Adulthood: The spider reaches the stage of sexual maturity in adulthood, where a new life cycle begins upon mating, and the life span of the spider varies in different types, but it lives from about one to two years, and what should be noted is that the life span of females is longer than males who often die after mating .

Spider food

The spider feeds on many organisms; Like insects and other spiders, in addition to small birds, frogs, reptiles and others, it also has the ability to sense the movement of prey, see it and distinguish between them, and what should be noted is that spiders have pointed front appendages such as fangs at the front of the head and chest called chelicerae, in addition to To pedipalps to catch prey, as spiders can obtain their food in several ways, as they may produce a toxin with the help of some enzymes to paralyze the movement of the prey, causing tissue damage and death, or some spiders may penetrate the skin and suck blood using special mouth parts to do so Or by weaving a web of silk threads that stick to the prey.

Habitat of the spider

All continents of the world except Antarctica are home to the spider, but many species live in the tropics more than temperate, and they are found in the Himalayas at an altitude of approximately 5,000 meters, in addition to most of them live on land except for the Eurasian species that lives on the water surface Fresh, there are a few species of spiders that make their living on the surface of beaches, fresh and salt water.

Cobwebs

The spider makes cobwebs from a strong protein filament called silk, which produces seven different types of it, so the spiders are classified according to the type of web they make, including: the tangled web spider, the circular web spinner, the funnel web spider, and the incubator web spider, [14] Spiders produce silk for several purposes, including: protecting themselves from falling, making egg bags, wrapping prey by making nets, and building their own housing and burrows.

The process of producing silk is carried out by pressing the spider to its abdomen after making it by several types of silk glands that have channels connected to the spindles and have external openings, where the muscle valves control the rate of silk flow, and there are 7 types of glands in spiders weaving networks, including:

Ring Glands: The silk produced by the Aciniform glands encapsulate the prey.

The ampullate glands produce silk that is used for drawing sutures.

Cylindrical glands: The cylindrical glands produce the silk used to make abdominal bags.

Silk glands above the stomach: The silk glands above the stomach (Epigastric silk glands) produce silk that is used to provide a surface for placing sperm on it, so it is found in male spiders.

Spider venom and stings

Spider venom does not pose a threat to humans except in some species. Such as the black widow spider, which has a strong neurotoxin, and the brown recluse spider, whose toxin spoils the tissues and leaves a deep hole in it. [17] The venom of the spider is made from a mixture of chemicals such as proteins, peptides, sugars and other substances to kill its prey or Paralyzing them, or breaking down tissues in order to obtain their nourishment in a liquid state, [18] It is worth noting that all spiders produce venom except for the family of "Uloboridae", where they lack specialized poison glands [19] and there are two types of toxins; They:

Neurotoxins: Neurotoxic Venoms affect the nervous system, as they prevent nerve impulses from reaching the muscles, where stiffness and contraction occur in muscles, disrupting body functions, and may paralyze the entire nervous system due to increased production of neurotransmitters. Such as acetylcholine and norephinephrine.

Cytotoxins: cytotoxic venoms affect tissues, causing skin ulcers and blisters, and causing damage and death.

The difference between a female spider and a male spider

Color: The colors of spiders vary from one species to another, but usually the colors of male spiders are more vivid than the female, as the male black widow spider appears in its light colors, and on its back are red or pink spots, while the female is black in color and on her stomach a red spot in the form of an hourglass However, this trait does not apply to the golden silk spider, as the female has a more vivid color than the dark brown male.

Size: It is believed that the size of the females is greater due to their need to produce offspring, as the female golden silk spider is 6 times the length of the male, in addition to several other species as well, such as: the black widow and the jumping spider.

Legs: Male spiders have longer legs than females, because they need them in the process of catching, and while they roam farther from the net in which the female stays.

Foot tentacles: It can be observed through a microscope that the foot tentacles in males are more swollen than in females.

The amount of venom: Female spiders need more venom to protect their web that does not leave it, and it should be noted that the venom bags of some male spiders are ineffective.

Spiders' life span: Spiders die before reaching old age due to predators, parasites, or diseases. Most of them live for several months, and some for years if they remain in their habitat and burrow. Females have a longer life compared to males, for example a female tarantula lives for 25 years, that is, 15 years more than males.

Sana Aldwikat

Mawdoo3

 

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