abdomen. Despite this shift, urticating hairs nonetheless retain unique characteristics that render them visually distinct from abdominal bristles, such as their tendency to cover only a portion instead of the entirety of the opisthosoma. Types There are seven different types of urticating hair known in tarantulas, varying in size and shape, particularly the distribution of barbs. Type I (0.2–0.6 mm) Type II (0.5–1.5 mm) Type III (0.3–1.2 mm) Type IV (0.06–0.2 mm) Type V Type VI Type VII Each type of urticating hair is believed to target different enemies. Defined targets for some bristle types are unknown. Type II is usually not kicked off by the tarantula, rather delivered by direct contact. However, there is at least one aviculariine species - Caribena versicolor - which can kick type II urticating hairs off of the abdomen, similarly to species from the subfamily Theraphosinae. Tarantulas from the genera Avicularia, Pachistopelma and Iridopelma possess Type II hairs. (Toni Hoover, 1997) Type III urticating hairs are most efficient for defense against vertebrates and invertebrates. Types III and IV are the most irritating to mammalian predators. Types particular to species Not all urticating hair types are exhibited by each species of tarantula. Type II urticating hairs can be found in the genera Avicularia, Iridopelma and Pachistopelma (subfamily Aviculariinae). Type I and III urticating hairs are representative on a wide diversity of large bodied genera in the subfamily Theraphosinae Lasiodora and Acanthoscurria Nhandu spp., Megaphobema spp., Sericopelma spp., Eupalaestrus spp., Proshapalopus spp., Brachypelma spp., Cyrtopholis spp., and others, although some only have Type I in mature males. Unusually, Type III urticating hair is found alone on the species of Theraphosa spp., but these otherwise are similar to many species that also have Type I hairs. Type III alone is found in many 'dwarf' new world genera Hapalopus spp.. Type IV is found in several South American genera Grammostola, Euathlus etc. (exhibits types III and IV). Type V urticating hair is typical of the species of genus Ephebopus. They are located on the pedipalps. They are much shorter and lighter in contrast with other types of urticating hair. These are easily thrown by the spider into the air. Type VI urticating hair is found in the genus Hemirrhagus. Genera with the most urticating hairs are Lasiodora, Grammostola and Acanthoscurria. Defensive behavior New World tarantulas will, at the moment of danger, turn toward the attacker and briskly rub