Urticating Hair,Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.As mentioned previously, New World species have urticating hairs on their opisthosomas. When alarmed, the spiders can brush off the hairs with their hind legs, which allows them to become airborne. Exposure to these hairs can occur from direct contact with the spider or indirectly from the animal's environment, especially when cleaning and replacing substrate. Each urticating hair is covered by hundreds of small hooks and can cause severe itching when it makes contact with the They are also one of the only arboreal tarantulas that possess urticating hairs. These hairs are unique in their structure among all.tarantulas. Five of the six described types of urticating hairs attach to the spider's body by a stalk on the opposite end of the hair from the penetrating end. For pinktoes, the urticating hair is attached to the cuticle of the spider by a stalk on the hair near (but not at) the piercing end. Pinktoe tarantulas can be abundant in parts of their range. They are the only A given species may have more than one type of urticating hair. Bald patches on the back of the abdomen (Figure 24.6) Figure 24.7 Urticating hairs of tarantulas (Theraphosidae). (A) Hairs of Avicularia surinamensis embedded in skin of young mouse; (B) basal tip of Type II hair of A. surinamensis, with backwarddirected barbs that help to work the hair into skin; (C).Type IV hair of unidentified tarantula from Chile that causes inflammation of respiratory passages of small mammals.There are four morphologic types of urticating hairs. Tarantulas within the United States possess only type I hairs, which do not penetrate the skin as deeply as do type III hairs. Type II hairs are incorporated into the silk web retreat and are not thrown off by the spider. Type III hairs can penetrate up to 2 mm (0.8 inch) into human skin. This is the type of hair most likely to cause inflammation. They are typically found on Mexican, Caribbean, and Central and South American species.In the case described in these articles the section of a hair was found in the middle of the nodules. The setae probably come from caterpillars.of the arctiid Spilosoma virginica. Other cases have been caused In general terms the principal cytopathologic changes produced in human beings and animals by phanerotoxic exogenous Lepidoptera with urticating larval forms are as follows. In the tegument, congestion, basal infiltration and edema (FOOT, 1922; MATTA, 1922). In the dermis (1991) and PerezMiles (1992a) considered Aviculariinae and Theraphosinae as sister groups, based on the presence of urticating hair. However, Aviculariinae have type II urticating hair (Cooke et al. 1972), but Theraphosinae have only types I, HI, and IV. There is no evidence of homology among these hairs, considering their structural differences and the presence of two hair types together in.individuals of the same species. Despite this, a close relationship between Aviculariinae Coville, produce phytobezoars similar to those commonly produced by hair. Dr. Trelease has described similar bezoars from the barbed trichomes and spines of cacti. Millet and barley awns are known to produce similar balls in horses as well as in cattle. Corn stalks, when eaten with an insufficient amount of water, produce impaction. This has, however, been attributed to other causes also. Bloat is known to follow the use Fig. 18b. Urticating hairs and cutting leaves, a. Urticating hair.3. Glandular hairs of epidermis, as in stinging nettles, protect plants from herbivorous animals. 4. Stomata help in gaseous exchange between the internal tissues.and the environment. Fig. 31. A— Stellate hair of Allyssum; B — Glandular hair of Pelargonium: C— Short glandular hair of Layandula; D— Floccose hair of Malva; E— Glandular hair of Solanum, F— Urticating hair of Vertascum; G— Stinging hair of Cestus. 5. Unicellular roots hairs help in the absorption of soil water. 2.