Bites and treatment
Despite their often scary appearance and reputation, none of the true tarantulas are known to have a bite which is deadly to humans. In general the effects of the bites of all kinds of tarantulas are not well known. While the bites of many species are known to be no worse than a wasp sting, accounts of bites by some species are reported to be very painful. Because other proteins are included when a toxin is injected, some individuals may suffer severe symptoms due to an allergic reaction rather than to the venom. For both those reasons, and because any deep puncture wound can become infected, care should be taken not to provoke any tarantula into biting. Tarantulas are known to have highly individualistic responses. Some members of species generally regarded as aggressive can be rather easy to get along with, and sometimes a spider of a species generally regarded as docile can be provoked. Anecdotal reports indicate that it is especially important not to surprise a tarantula.
Some species of tarantula, particularly those of the Poecilotheria varieties from South Asia (India, Sri Lanka, etc) are known to possess uniquely potent venom which can cause serious muscle cramps, temporary and localized paralysis, and deep sleep (sometimes compared to coma-like symptoms) in addition to the severe pain associated with the bite itself. In addition to the inherent risk of their venom these spiders are also notoriously easy to provoke and remarkably fast strikers making them not suitable pets for anyone but experienced handlers. Common names of some of these tarantula include Sri Lankan Ornamental, Salem Ornamental, Pedersen's Ornamental, Indian Ornamental, Fringed Ornamental, Salem Ornamental, et al.
New World tarantulas (those found in North and South America) are equipped with urticating hairs on their abdomen, and will almost always use these as a first line of defense. These hairs will irritate sensitive areas of the body and especially seem to target curious animals who may sniff these hairs into the mucous membranes of the nose. These hairs generally do not irritate the hands or other tough areas of skin. Some species have more effective urticating hairs than others. The goliath birdeater is one species known for its particularly irritating urticating hairs. Old world tarantulas (from Asia) have no urticating hairs, and are more likely to attack when disturbed. Old world tarantulas often have more potent, medically significant venom.
Before biting, tarantulas may signal their intention to attack by rearing up into a "threat posture", which may involve raising their prosoma and lifting their front legs into the air, spreading and extending their fangs, and (in certain species) making a loud hissing noise called Stridulating. Their next step, short of biting, may be to slap down on the intruder with their raised front legs. If that response fails to deter the attacker they may next turn away and flick urticating hairs toward the pursuing predator. Their next response may be to leave the scene entirely, but, especially if there is no line of retreat, their next response may also be to whirl suddenly and bite. Tarantulas can be very deceptive in regard to their speed because they habitually move very slowly, but are able to deliver an alarmingly-rapid bite when sufficiently motivated.
There are, however, dangerous spiders which are not true tarantulas but which are frequently confused with them. It is a popular urban legend that there exist deadly varieties of tarantulas somewhere in South America, a theory which provides the basis of the story in the American film Arachnophobia. This claim is often made without identifying a particular spider although the "banana tarantula" is sometimes named. A likely candidate is the dangerous Brazilian wandering spider (Phoneutria nigriventer), as it is sometimes found hiding in clusters of bananas and is one of several spiders called the "banana spider." It is not a tarantula but it is fairly large (4-5 inches long), somewhat hairy, highly venomous to humans, and is regarded as aggressive. Another dangerous type of spider confused with tarantulas are the venomous funnel-web tarantulas, which despite their name are not theraphosids. The best known of these is the Sydney funnel-web spider (Atrax robustus), a spider which is aggressive, highly venomous, and prior to the development of antivenom in the 1980s, was responsible for numerous deaths in Australia. These spiders are members of the same suborder as the true tarantulas, but are not found in family Theraphosidae.
*goose bumps*
