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Centipedes (from Latin prefix ''ラテン語:centi-'', "hundred", and ''ラテン語:pes, pedis'', ''"foot"'') are arthropods belonging to the class Chilopoda of the subphylum Myriapoda. They are elongated metameric creatures with one pair of legs per body segment. Despite the name, centipedes can have a varying number of legs, ranging from 30 to 354. Centipedes always have an odd number of pairs of legs. Therefore, there is no centipede with exactly 100 legs. A key trait uniting this group is a pair of venom claws or ''forcipules'' formed from a modified first appendage. Centipedes are a predominantly carnivorous taxon. Size can range from a few millimetres in the smaller lithobiomorphs and geophilomorphs to about in the largest scolopendromorphs. Centipedes can be found in a wide variety of environments. Centipedes normally have a drab coloration combining shades of brown and red. Cavernicolous (cave-dwelling) and subterranean species may lack pigmentation and many tropical scolopendromorphs have bright aposematic colours. Worldwide, there are estimated to be 8,000 species of centipede, of which 3,000 have been described. Centipedes have a wide geographical range where they even reach beyond the Arctic Circle.〔 Centipedes are found in an array of terrestrial habitats from tropical rainforests to deserts. Within these habitats, centipedes require a moist micro-habitat because they lack the waxy cuticle of insects and arachnids, and so lose water rapidly through the skin.〔 Accordingly, they are found in soil and leaf litter, under stones and dead wood, and inside logs. Centipedes are among the largest terrestrial invertebrate predators and often contribute significantly to the invertebrate predatory biomass in terrestrial ecosystems. ==Description== Centipedes have a rounded or flattened head, bearing a pair of antennae at the forward margin. They have a pair of elongated mandibles, and two pairs of maxillae. The first pair of maxillae form the lower lip, and bear short palps. The first pair of limbs stretch forward from the body to cover the remainder of the mouth. These limbs, or maxillipeds, end in sharp claws and include venom glands that help the animal to kill or paralyse its prey. Many species of centipedes lack eyes, but some possess a variable number of ocelli, which are sometimes clustered together to form true compound eyes. However, these eyes are only capable of discerning light and dark, and have no true vision. In some species the first pair of legs at the head end of the centipede act as sense organs similar to antennae, but unlike the antennae of most other animals, they point backwards. An unusual sense organ found in some groups are the organs of Tömösváry. These are located at the base of the antennae, and consist of a disc-like structure with a central pore surrounded by sensory cells. They are probably used for sensing vibrations, and may even provide a sense of hearing.〔 Forcipules are a unique feature found only in centipedes and in no other arthropods. The forcipules are modifications of the first pair of legs, forming a pincer-like appendage always found just behind the head. Forcipules are not true mouthparts, although they are used in the capture of prey items, injecting venom and holding onto captured prey. Venom glands run through a tube almost to the tip of each forcipule.〔 Behind the head, the body consists of fifteen or more segments. Most of the segments bear a single pair of legs, with the maxillipeds projecting forward from the first body segment, and the final two segments being small and legless. Each pair of legs is slightly longer than the pair immediately in front of it, ensuring that they do not overlap, and therefore reducing the chance that they will collide with each other while moving swiftly. In extreme cases, the last pair of legs may be twice the length of the first pair. The final segment bears a telson and includes the openings of the reproductive organs.〔 As predators, centipedes mainly use their antennae to seek out their prey. The digestive tract forms a simple tube, with digestive glands attached to the mouthparts. Like insects, centipedes breathe through a tracheal system, typically with a single opening, or spiracle on each body segment. They excrete waste through a single pair of malpighian tubules.〔 ''Scolopendra gigantea'', also known as the Amazonian giant centipede, is the largest existing species of centipede in the world, reaching over in length. It is known to eat lizards, frogs, birds, mice, and even bats, catching them in midflight, as well as rodents and spiders. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Centipede」の詳細全文を読む スポンサード リンク
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