Arachnids (arachnida) Animal Arthropoda chelicerae Amon biggest one outline. Including spiders, scorpions and ticks and mites, etc., into the body and rear body precursor. Precursor composed of six, on the back of the package with a typically hard carapace, ventral one or more blocks of the web, or appendages of the base section cover. After the body portion 12 consisting of, in addition to scorpion class, no majority of the abdomen into two distinct parts, the abdomen and the precursor of mites have one. Monocular no more than 12. After the spider's body between the precursor through the abdomen and connected to the handle. After the body is usually no appendages. Dioecious. Known around the world more than 50,000 kinds, the vast majority of terrestrial, only a few spider mites and one kind of aquatic. Most species are carnivorous arachnids. Book lungs or tracheal breathing, and some both. Arachnida class generally do not spread. But there are a few types of spiders in flight habits. Endurance of hunger Arachnida class strong. Arachnida class do not like hot, often hidden under rocks or leaves, or burrowing camp life, the extra activities at night. There are several scorpion can only survive in wet locations, and to drink plenty of water. But in the heat of the desert, there are several blind scorpion and spider still survive. Arachnids can be divided into four sub-classes, 16 orders, which total three extant species subclass 11 orders. Arachnids predator insects in many species, there is a certain role in maintaining ecological balance. Some scorpion and spider species can be used as medicine. Mites are parasites of many plants and animals; scorpion, pseudo scorpion and spider venom may harm or death to humans and animals.
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Outline
Arachnids (Arachnida) are arthropods door chelicerae animal Amon biggest one outline. Including spiders, scorpions and ticks and mites, etc., into the body and rear body precursor. Precursor composed of six, on the back of the package with a typically hard carapace, ventral one or more blocks of the web, or appendages of the base section cover. After the body portion 12 consisting of, in addition to scorpion class, most digital arachnids longer abdomen into distinct parts, and the body section has a combined trend. Abdominal precursor mites have one. Monocular no more than 12. Precursors have six pairs of appendages. Chelicerae front of the mouth, Section 2-3, clamp-like non-pincer. Pedipalps 6, clamp-like or foot shape. Pereiopod 7. The end of the tarsus have claws. After the spider's body between the precursor through the abdomen and connected to the handle. After the body is usually no appendages. Dioecious. Section 2 of the ventral body gonopores open in the post. Known around the world more than 50,000 kinds, the vast majority of terrestrial, only a few spider mites and one kind of aquatic.
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Physiological characteristics
Digestion: Most species are carnivorous arachnids, when feeding, some advance in vitro digestion, that is, when the capture prey, first to touch the limb and chelicerae to kill and tear, and then spit the Central intestinal secretion digestive enzymes, so that part of the food to the mouth cavity in vitro digestion before then. After the food from the mouth into the pharynx and esophagus foregut, and then into the esophagus to the intestine from. In the intestinal secretory cells and absorptive cells. Secreting cells in vitro digestive enzymes in the gut after food to continue to complete digestion. Absorption of nutrients stored in the cell-cell multi-blind around the tube. Midgut extends to the rear of the abdomen, through short bowel (ie, hindgut) and leading to the anus. Excretion: excretory organs and glands of the base section Markov tubes, some types of both, or with only one. Gland located at the base sides of the front section of the body portion, a circular thin-walled balloon, immersed in the blood collected from the blood around the waste, through a coiled tube, the opening in the base section of the appendage. Base section gland from embryonic sac derived from the body cavity, no more than 4 pairs. Markov tube 1 to 2 pairs located in the midgut and hindgut phase at the rear. Wastes from the blood through the wall, routed the intestines. Nervous system: In addition to the more primitive scorpion class, the nervous system is highly concentrated. Brain located above the esophagus, the original composition of the brain and hindbrain. There are original brain visual cortex and the optic nerve to the brain through nerve chelicerae. The rest of the central nervous system in the bottom of the esophagus. Arachnids many kinds of purposes, originally located in the brain, and most or all of the ganglia of the abdomen to move forward, but with the lower esophageal ganglion touch limb merger. Most arachnids class has three kinds of sensory: sensory hair, eyes and joints sensory. Sensory hair covered the entire surface, with the limbs, especially much. Feel there is a class called Mao Mao listen, slim and long, base expanded into a small ball, sitting in a nest, and a nerve connected, can feel very weak vibrations and airflow. Various classes of spider-shaped eyes are similar. Cornea and lens together, the Department of the thickened portion of the stratum corneum. Crystal is a layer beneath the dermis called vitreous cells, then the following is a layer of light-sensitive retina cells. There behind the retina after retinal membranes. Photoreceptor cells or toward the light source (direct eye), or toward the retina membrane (indirect eye). After the film indirectly eye retina is reflective pigment layer. Some classes only a certain type of spider-shaped eyes; But there are many types (such as spiders) all have two kinds of eyes. Seam on the cuticle is feeling a slit-like fossa, there is a very thin gap at masking film, film below with a pass out of the sensory cells in contact with the hairy projections. Number of joints feeling's probably many, some single, some groups called piano-shaped device. Has on the body and appendages most arachnids class. Some spiders up to 3000, of which about half hordes. This receptor can be subtle changes in the external skeletal tension react and have their own feelings and detect vibration function. Breath: arachnid book lungs or tracheal breathing, and some both. Book more primitive lung, may change comes from the book gills, the structure is very similar, but the book lungs in the body, land suitable for breathing, in pairs, located in the ventral abdomen. Scorpion book lungs up to four pairs of each section on a belly. Lung by the abdominal abdominal wall retraction book into a capsule made of the side wall and folded into many leafy flap book pages folded in shape, hence the name. Sinus blood from flowing into the abdominal flap. Book of the hole into the pulmonary air into the gap between the two halves, the gas exchange. Do not form folds are formed on the side wall of a valve chamber, the valve chamber flap inward towards the gap between outward through the book lungs holes. Some gas chamber on the back muscle, the contraction of the expansion chamber, lung hole is open book; but most of the gas diffusion means and ventilation. Insect tracheal system similar to, but different origins, it is generally considered less water than the book lung damage. Only the type of tracheal breathing, circulatory system can not afford much of a role in terms of oxygen transport. On the contrary, there is a scorpion book lungs and the blood of many species of spiders in the respiratory pigments - hemocyanin. Cycle: Heart almost all in the first half of the abdomen. Low heart kind of sub-section, with the corresponding section of the abdomen, heart hole pair per session. Scorpion heart of seven, but in different groups have different degrees of degradation, some mites or even disappear completely. Heart forward through the aorta to the front of a large precursor, a small artery to the latter part of the abdomen, from each section of the heart through a pair of small abdominal artery. Arteriolar blood flow into the tissue space eventually, and then aggregated to the abdominal sinus, lung contact with the book, and then by one or several intravenous tube back into the pericardial sinus. Reproduction: female and male bore holes are usually at 8 somites (ie, second abdominal segment) of the ventral surface. Gonads single or in pairs. Many Arachnida class to fine package indirect transfer sperm. Spider, scorpion, scorpion and other pseudo-class male courtship behavior, and different classes have different forms. Spider spider and avoid blind date no marriage dance. After the mother without some kind of spawning protection, or have died before the offspring hatch, but some species have larvae or oocysts protection act.
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Habits
Arachnida class generally do not spread. As long as there is plenty of food scorpion, do not move to far away. But there are a few types of spiders in flight habits. In summer, fruit mites can be attached to the foot past the insect migration. Occasionally can be attached to a pseudo-scorpion arachnids - scorpion flies, blind spider or other animals on foot. This may be due to hunger and food rich in place to move to. Endurance of hunger Arachnida class strong, scorpion ability hunger 14 months, a Filistata ability hunger 26 months, the ability of a hungry spider belly ball 30 months. Arachnida class do not like hot, often hidden under rocks or leaves, or burrowing camp life, the extra activities at night. Weaving spiders thick cuticle, individual greater than the general color is gorgeous. Hidden in the stones, under leaves or thin cuticle cave species can not live in that hot environment, it can not make long-distance travel. There are several scorpion can only survive in wet locations, and to drink plenty of water. Blind spider often drink water. Pseudo scorpion in a dry environment soon died. But in the heat of the desert, there are several blind scorpion and spider due to the surface with a layer of wax, can be well preserved water to survive.
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Distributed
Geographical distribution Arachnida class can be divided into four types: ① continuous distribution in tropical, subtropical, such as scorpions, spiders avoid date, no whip class, there are classes and whip spider tarantula purpose; ② discontinuously distributed in tropical, subtropical, as required amphipods, abdominal section category, class and spiders split shield purposes ancient spider families; ③ distributed from the tropics to the temperate zone, such as the blind spider, pseudo-scorpion, spider mites and the purpose of most species; ④ distributed to the poles, some spiders, spiders and mites blind. Everest at 6,700 meters in the jumping spider may be found in the distribution of the world's tallest animal.
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Classification
Arachnids can be divided into four sub-classes, 16 orders, which total three extant species subclass 11 orders: The main purpose of arachnids wide belly subclass (Latigastra): scorpion mesh (Scorpiones), pseudo scorpion mesh (Pseudoscorpiones), blind spider mesh (Opiliones), the ancient terror mesh (Architarbi), Acari (Acarina). Chest subclass (Stethostoma): United Amphipoda (Haptopoda), the amphipod (Anthracomarti). Separate subclass (Soluta): Angle terror mesh (Trigotarbi). Handle belly subclass (Caulogastra): must foot mesh (Palpigradi), there whip mesh (Uropigi), split shield mesh (Schizomida), Chiquimula mesh (Kustarachnae), no whip mesh (Amblypygi), Araneae (Araneae), section abdominal mesh (Rici-nulei), to avoid day mesh (Solifugae). Some scholars have whip mesh, mesh and no whip crack shield mesh into one foot must mesh. Which the ancient terror mesh, mesh joint foot, hind foot mesh, mesh angle terror projects and Chiquimula five categories of extinct species; must foot mesh, no whip head and abdominal mesh section 3 orders has not yet been found in China.
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Kinship
Arachnids are terrestrial animals chelicerae, book lungs to breathe air. Book lung and limb mouth Gang book gills homologous, but has evolved to adapt to life on land respirator, cracks communicate with the outside world only in pairs. Limulus (limb mouth Gang swordtail mesh) developed abdominal appendages in arachnids class has been extremely degraded, leaving only part of the scorpion and spider, but has changed to a special structure, such as the comb plate or spinning device. As the book scorpion book lungs and gills in the horseshoe crab histologically very close, people think scorpion is arachnids most primitive group.
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Economic significance
Arachnids predator insects in many species, there is a certain role in maintaining ecological balance. Some scorpion and spider species can be used as medicine. Mites are parasites of many plants and animals; scorpion, pseudo scorpion and spider venom may harm or death to humans and animals.
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Wikipedia Encyclopedia
zhuxing gang Arachnids Arachnida Arthropoda chelicerae Amon biggest one animal classes, including spiders, scorpions and ticks mites, spider-shaped body into class precursors and rear body. Precursor composed of six, on the back of the package with a typically hard carapace, ventral one or more blocks of the web, or appendages of the base section cover. After the body portion 12 consisting of, in addition to scorpion class, most arachnids abdomen is no longer divided into two distinct parts, and the body section has a combined trend. Abdominal precursor mites have one. Known around the world more than 50,000 kinds, the vast majority of terrestrial, only a few spider mites and one kind of aquatic. Arachnids monocular no more than 12. Precursors have six pairs of appendages. Chelicerae front of the mouth, Section 2-3, clamp-like non-pincer. Pedipalps 6, clamp-like or foot shape. Pereiopod 7. The end of the tarsus have claws. After the spider's body between the precursor through the abdomen and connected to the handle. After the body is usually no appendages. Dioecious. Section 2 of the ventral body gonopores open in the post. Most arachnids kind of nutrition is carnivorous, feeding at the time, part of the first in vitro digestion, that is, when capturing prey, first to touch the limb and chelicerae to kill and tear, and then spit the Central intestinal secretion digestive enzymes, so that part of the food to the mouth cavity in vitro digestion before then. After the food from the mouth into the pharynx and esophagus foregut, and then into the esophagus to the intestine from. In the intestinal secretory cells and absorptive cells. Secreting cells in vitro digestive enzymes in the gut after food to continue to complete digestion. Absorption of nutrients stored in the cell-cell multi-blind around the tube. Midgut extends to the rear of the abdomen, through short bowel (ie, hindgut) and leading to the anus. Excretory gland excretory organ of the base section and Markov tubes, some types of both, or with only one. Gland located at the base sides of the front section of the body portion, a circular thin-walled balloon, immersed in the blood collected from the blood around the waste, through a coiled tube, the opening in the base section of the appendage. Base section gland from embryonic sac derived from the body cavity, no more than 4 pairs. Markov tube 1 to 2 pairs located in the midgut and hindgut phase at the rear. Wastes from the blood through the wall, routed the intestines. In addition to the more primitive nervous system of scorpion class, the nervous system is highly concentrated. Brain located above the esophagus, the original composition of the brain and hindbrain. There are original brain visual cortex and the optic nerve to the brain through nerve chelicerae. The rest of the central nervous system in the bottom of the esophagus. Arachnids many kinds of purposes, originally located in the brain, and most or all of the ganglia of the abdomen to move forward, but with the lower esophageal ganglion touch limb merger. Most arachnids class has three kinds of sensory: sensory hair, eyes and joints sensory. Sensory hair covered the entire surface, with the limbs, especially much. Feel there is a class called Mao Mao listen, slim and long, base expanded into a small ball, sitting in a nest, and a nerve connected, can feel very weak vibrations and airflow. Various classes of spider-shaped eyes are similar. Cornea and lens together, the Department of the thickened portion of the stratum corneum. Crystal is a layer beneath the dermis called vitreous cells, then the following is a layer of light-sensitive retina cells. There behind the retina after retinal membranes. Photoreceptor cells or toward the light source (direct eye), or toward the retina membrane (indirect eye). After the film indirectly eye retina is reflective pigment layer. Some classes only a certain type of spider-shaped eyes; But there are many types (such as spiders) all have two kinds of eyes. Seam on the cuticle is feeling a slit-like fossa, there is a very thin gap at masking film, film below with a pass out of the sensory cells in contact with the hairy projections. Number of joints feeling's probably many, some single, some groups called piano-shaped device. Has on the body and appendages most arachnids class. Some spiders up to 3000, of which about half hordes. This receptor can be subtle changes in the external skeletal tension react and have their own feelings and detect vibration function. Breathing arachnids book lungs or trachea breathing, and some both. Book more primitive lung, may change comes from the book gills, the structure is very similar, but the book lungs in the body, land suitable for breathing, in pairs, located in the ventral abdomen. Scorpion book lungs up to four pairs of each section on a belly. Lung by the abdominal abdominal wall retraction book into a capsule made of the side wall and folded into many leafy flap book pages folded in shape, hence the name. Sinus blood from flowing into the abdominal flap. Book of the hole into the pulmonary air into the gap between the two halves, the gas exchange. Do not form folds are formed on the side wall of a valve chamber, the valve chamber flap inward towards the gap between outward through the book lungs holes. Some gas chamber on the back muscle, the contraction of the expansion chamber, lung hole is open book; but most of the gas diffusion means and ventilation. Similar insect tracheal system, but from
Araneida