Tarantula walking, close up

Black and orange tarantula walking in slow motion close up. Hairy arachnid in its habitat. Mexican Orange-kneed Tarantula (Euathlus smithii) Tarantulas comprise a group of large and often ″hairy″ spiders of the family Theraphosidae (technically, spiders possess setae, not true hairs[2]). Currently, about 1,000 species have been identified.[3] The term tarantula is usually used to describe members of the family Theraphosidae, although many other members of the same infraorder (Mygalomorphae) are commonly referred to as "tarantulas" or "false tarantulas". Some of the more common species have become popular in the exotic pet trade. Many New World species kept as pets have urticating hairs that can cause irritation to the skin, and in extreme cases, cause damage to the eyes.[4] Like all arthropods, the tarantula is an invertebrate that relies on an exoskeleton for muscular support.[5] Like other Arachnida, a tarantula’s body comprises two main parts, the prosoma (or cephalothorax) and the opisthosoma (or abdomen). The prosoma and opisthosoma are connected by the pedicel, or pregenital somite. This waist-like connecting piece is actually part of the prosoma and gives the opisthosoma a wide range of motion relative to the prosoma. Tarantula sizes can range from as small as the size of a BB Pellet[6] to as large as a dinner plate when the legs are fully extended.[7][8] Depending on the species, the body length of tarantulas ranges from 0.180 to 4.33071 in (5 to 110 mm),[6][9] with leg spans of 8–30 cm (3–12 in).[citation needed] Leg span is determined by measuring from the tip of the back leg to the tip of the front leg on the opposite side. Some of the largest species of tarantula may weigh over 85 g (3 oz); the largest of all, the goliath birdeater (Theraphosa blondi) from Venezuela and Brazil, has been reported to attain a weight of 170 g (6.0 oz)[10] and a leg-span up to 30 cm (12 in), males being longer and females greater in girth. The fang size of this tarantula reaches a maximum of 3.8 cm (1.5 in).[10] A tarantula next to a U.S. size 11 shoe, to show scale, taken near Austin, Texas Tarantula native to the Mojave Desert searches for burrow. Aphonopelma mojave. Tarantula native to the Mojave Desert searches for a burrow. The name "tarantula" is also incorrectly applied to other large-bodied spiders, including the purseweb spiders or atypical tarantulas, the funnel-webs (Dipluridae and Hexathelidae), and the "dwarf tarantulas". These spiders are related to tarantulas (all being mygalomorphs), but are classified in different families. Huntsman spiders of the family Sparassidae have also been termed "tarantulas" because of their large size, when, in fact, they are not related, and instead belong to the infraorder Araneomorphae. The element pelma in genus names Many theraphosid genera have names, either accepted or synonymous, containing the element pelma. This can be traced back to Carl Ludwig Koch in 1850,[13] who in describing his new genus Eurypelma wrote "Die Sammetbürste der Fussohlen sehr breit",[14] literally 'the velvet-brush of the footsole very wide'. German arachnologists use the word Fuß to refer to the tarsus (the last article of a spider's leg).[15] Translations of Sammetbürste into Latin use the word scopula.[16] Hence in English arachnological terminology, Koch meant 'the scopula of the base of the tarsus very wide'. Eury- is derived from the Greek εὐρύϛ, meaning 'wide', while πέλμα (pelma) means 'the sole of the foot',[13] thus paralleling Koch's use of Fußsohle (in modern spelling). Thus Eurypelma literally means 'wide footsole'; however, arachnologists have conventionally taken pelma in such names to refer to the scopula, so producing the meaning 'with a wide scopula'.[13] Tarantula at the mouth of its burrow Most species of North American tarantulas are brown. Elsewhere, species have been found that variously display cobalt blue (Cyriopagopus lividus), black with white stripes (Aphonopelma seemanni), yellow leg markings (Eupalaestrus campestratus), metallic blue legs with vibrant orange abdomen and green prosoma (Chromatopelma cyaneopubescens). Their natural habitats include savanna, grassland such as in the pampas, rainforest, desert, scrubland, mountains, and cloud forest. They are generally classed among the terrestrial types. They are burrowers that live in the ground. Tarantulas are becoming increasingly popular as pets and some species are readily available in captivity.