Tarantula
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| Tarantula | ||||||||||||||
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Brachypelma smithi | ||||||||||||||
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| Diversity | ||||||||||||||
| 113 genera, 897 species | ||||||||||||||
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| Acanthopelminae |
Tarantula is the common name for a group of hairy, often very large spiders belonging to the family Theraphosidae, of which 800 species have been identified. Tarantulas hunt prey on the ground and do not spin webs unless they live in a tunnel. They line their tunnel with web to catch wandering prey. They mainly eat insects and other arthropods, caught by speed or ambush. The biggest tarantulas can kill animals as large as lizards, mice, or birds. Most tarantulas are harmless to humans, and some species are popular in the exotic pet trade while others are eaten as food. These stocky, fearsome-looking spiders are found in tropical and desert regions around the world.
The name tarantula comes from the town of Taranto in Italy and was originally used for an unrelated species of European spider. (See Wolf spider for more information about this spider). In North America the term tarantula commonly refers to species of theraphosids found in the Americas. In Africa, theraphosids are frequently referred to as baboon spiders. Asian forms are known as earth tigers or bird spiders. Australians refer to their species as barking spiders, whistling spiders, or bird spiders. People in other parts of the world also apply the general name mygales to theraphosid spiders.
There are other species also referred to as tarantulas outside this family; the evolution of the name Tarantula is discussed below. This article primarily concerns the theraphosids.
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[edit] Morphology
Like all arthropods, the tarantula is an invertebrate that relies on an exoskeleton for muscular support. A tarantula’s body consists of two main parts, the prosoma or the cephalothorax (the former is most often used because there is no analogous "head") and the abdomen or opisthosoma. The cephalothorax and opisthosoma are connected by the pedicle or what is often called the pregenital somite. This waist-like connecting piece is actually part of the prosoma and allows the opisthosoma to move in a wide range of motion relative to that of the cephalothorax.
Depending on the species, the body length of tarantulas range from 2.5 - 10 cm (1-4 inches), with 8-30 cm (3 to 12 inch) leg spans (their size when including their legs). Legspan is determined by measuring from the tip of the back leg to the tip of the front leg on the same side, although some people measure from the tip of the first leg to the tip of the fourth leg on the other side. The largest species of tarantulas can weigh over 90 grams (3 ounces). One candidate for the title of the largest of all species, the Theraphosa blondi (goliath birdeater) from Venezuela and Brazil has been reported to have a weight of 3 ounces and a leg span of up to 13 inches (33 cm). The males have the long length, and the females have lots of girth.
Theraphosa apophysis (the pinkfoot goliath) was described 187 years after the Goliath birdeater; therefore its characteristics are not as well attested. However, legspans of up to 33 cm (13 inches) have been reported for that species. T. blondi is generally thought to be the heaviest tarantula, and T. apophysis the largest legspan. Two other species, Lasiodora parahybana and Lasiodora klugi, (the Brazilian salmon birdeater) gets very large and rivals the size of both Theraphosa blondi and Theraphosa apophysis, and some have even made claims to same size and even bigger sizes than the two Theraphosa species.
The majority of tarantulas are brown or black, drab, and are adapted to escaping notice; however, some species have more extensive coloration patterns, ranging from cobalt blue (Haplopelma lividum), black with white stripes (Eupalaestrus campestratus or Aphonopelma seemanni), to metallic blue legs with vibrant orange abdomen (Chromatopelma cyaneopubescens, green bottle blue). Their natural habitats include savanna, grasslands such as the pampas, rainforests, deserts, scrubland, mountains and cloud forests. They are generally divided into terrestrial types (that frequently make burrows) and arboreal types that build tented shelters well off the ground. The more easily spotted tarantulas tend to be more aggressive and some of these aggressive species have venom that can cause severe pain for extended periods.
[edit] Appendages
The eight legs, the two chelicerae with their hollow fangs, and the pedipalps are attached to the prosoma. The chelicerae are two single segment appendages that are located just below the eyes and directly forward of the mouth. The chelicerae contain the venom glands that vent through the fangs. The fangs are hollow extensions of the chelicerae that inject venom into prey or animals that the tarantula bites in defense, and they are also used to masticate (chew). These fangs are articulated so that they can extend downward and outward in preparation to bite or can fold back toward the chelicerae as a pocket knife blade folds back into its handle. The chelicerae of tarantulas completely contain the venom glands and the muscles that surround them and can cause the venom to be forcefully injected into prey.
The pedipalpi are two six–segment appendages connected to the thorax near the mouth and protruding on either side of both chelicerae. In most species of tarantula the pedipalpi contain sharp jagged plates used to cut and crush food often called the coxae or maxillae.As with other spiders, the terminal portion of the pedipalpi of males function as part of its reproductive system. Male spiders spin a silken platform on the ground onto which they release semen from glands in their opistoma. Then they insert their pedipalps into the semen, absorb the semen into the pedipalps, and later insert the pedipalps (one at a time) into the reproductive organ of the female, which is located in her abdomen. The terminal segments of the pedipalps of male tarantulas are larger in circumference than those of a female tarantula.
A tarantula has four pairs of legs but eight pairs of total appendages. Each leg has seven segments which from the prosoma out are: coxa, trochanter, femur, patella, tibia, tarsus and pretarsus, and claw. Two or three retractable claws are at the end of each leg. These claws are used to grip surfaces for climbing. Also on the end of each leg, surrounding the claws, is a group of hairs. These hairs, called the scopula, help the tarantula to grip better when climbing surfaces like glass. The fifth pair of legs are the pedipalps which aid in feeling and mating for a mature male. The sixth pair of appendages are the fangs. It is believed that the fangs were at one time legs, but now they are used as weapons, masticating, matings, occasional for mobility. They are mostly used to subdue prey.
The seventh and eighth pairs of appendages are the four spinnerettes, which also are hypothesized by some to have been leglike appendages. When walking, a tarantula's first and third leg on one side move at the same time as the second and fourth legs on the other side of his body. The muscles in a tarantula's legs cause the legs to bend at the joints, but to extend a leg, the tarantula increases the pressure of blood entering the leg.
Tarantulas, like almost all other spiders, have their spinnerets at the end of the opisthosoma. Unlike spiders that on average have six, tarantulas have two or four spinnerets. Spinnerets are flexible tubelike structures from which the spider exudes its silk. The tip of each spinneret is called the spinning field. Each spinning field is covered by as many as one hundred spinning tubes through which silk is produced. This silk hardens on contact with the air to become a thread like substance.
[edit] Digestive system
The tarantula’s mouth is located under its chelicerae on the lower front part of its prosoma. The mouth is a short straw-shaped opening which can only suck, meaning that anything taken into it must be in liquid form. Prey with large amounts of solid parts such as mice must be crushed and ground up or predigested, which is accomplished by spraying the prey with digestive juices that are excreted from openings in the chelicerae.
The tarantula’s digestive organ (stomach) is a tube that runs the length of its body. In the prosoma this tube is wider and forms the sucking stomach. When the sucking stomach's powerful muscles contract, the stomach is increased in cross-section, creating a strong sucking action that permits the tarantula to suck liquids up through the mouth and into the intestines. Once the liquified food enters the intestines, it is broken down into particles small enough to pass through the intestine walls into the haemolymph (blood stream) where it is distributed throughout the body.
[edit] Nervous system
A tarantula's central nervous system (brain) is located in the bottom of the inner prosoma. The central nervous system controls all of the body's activities. A tarantula maintains awareness of its surroundings by using its sensory organs, setae. Although it has eyes, and the eyes of arboreal tarantulas appear to be relatively good, a tarantula’s sense of touch is its keenest sense and it often uses vibrations given off by its prey's movements to hunt. Some of a tarantula's hairs are very sensitive organs and are used to sense chemical signatures, vibration, wind direction and possibly even sound. Tarantulas are also very responsive to the presence of certain chemicals. A tarantulas main senses would perhaps be like being able to taste-smell the world.
The eyes, which, unlike those of insects, are simple lenses, are located above the chelicerae on the forward part of the prosoma. They are small and usually set in two rows of four. Most tarantulas are not able to see much more than light, darkness, and motion. Arboreal tarantulas see better than terrestrial tarantulas.
[edit] Respiratory system
In all types of tarantulas there are two book lungs (breathing organs). The book lungs are located in a cavity inside the lower front part of the abdomen near where the abdomen connects to the cephalothorax. Air enters the cavity through a tiny slit on each side of and near the front of the abdomen. Each lung consists of 15 or more thin sheets of folded tissue arranged like the pages of a book. These sheets of tissue are supplied by many blood vessels. As air enters each lung, oxygen is taken into the blood stream through the blood vessels in the lungs. Needed moisture may also be absorbed from humid air by these organs.
[edit] Circulatory system
A tarantula’s blood is a pale liquid; an oxygen-transporting protein is present (the copper-based hemocyanin) but not enclosed in blood cells like the erythrocytes of mammals. A tarantula’s blood is not true blood but rather a liquid called haemolymph, or hemolymphy. There are at least four types of hemocytes, or hemolymph cells. The tarantula’s heart is a long slender tube that is located along the top of the opisthosoma. The heart is neurogenic as opposed to myogenic, so nerve cells instead of muscle cells initiate and coordinate the heart. The heart pumps hemolymph to all parts of the body through open passages often referred to as sinuses, and not through a circular system of blood vessels. If the exoskeleton were to be breached, loss of hemolymph could kill the tarantula unless the wound were small enough that the hemolymph could dry and close the wound.
[edit] Hairs
Besides the normal hairs covering the body of tarantulas, some also have a dense covering of irritating hairs (about 10,000 per mm²),[1] called urticating hairs, on the opisthosoma, that they sometimes use as a protection against enemies. These hairs are only present on some New World species of the subfamilies of Ischnocolinae, Aviculariinae, Grammostolinae and Theraphosinae,[1] and are absent on specimens of the Old World. They help in phylogenetic studies of Theraphosinae.[2]
These fine hairs are barbed, and designed to urticate, but do not contain venom. Some species can 'kick off' these hairs: they are launched into the air at a target. Tarantulas also use these hairs for other means; using them to mark territory or to line the web or nest (the latter such practice may discourage flies from feeding on the spiderlings).
To predators and other kinds of enemies, these hairs can range from being lethal to simply being a deterrent. With humans, they can cause irritation to eyes, nose, and skin, and more dangerously, the lungs and airways, if inhaled. The symptoms range from species to species, from person to person, from a burning itch to a minor rash. In some cases, tarantula hairs have caused permanent damage to human eyes.[3] Tarantula hair has been used as the main ingredient in the novelty item "itching powder".[citation needed] Some tarantula enthusiasts have had to give up their spiders because of allergic reactions to these hairs (skin rashes, problems with breathing, and swelling of the affected area).
Some setae are used to stridulate which makes a hissing or buzzing sound. These hairs are usually found on the chelicerae. Stridulation seems to be more common in Old World species. Many of the New World species, especially those in the Ischnocolinae, Aviculariinae, Grammostolinae, and Theraphosinae subfamilies, have urticating hairs (barbed hairs often kicked at or pushed into predators to discourage their approach) on certain parts of their bodies, but especially the top of the opisthosoma. These urticating hairs can be flicked onto predator animals such as mice to cause itchiness, burning, swelling, redness, and other irritation. These hairs, like the quills of porcupines, are serious defensive weapons. Even large animals like humans can be blinded if urticating hairs are delivered to their eyes and then left untreated. Lung damage is another possible danger. Some people react especially badly to urticating hairs, notably people with dermatitis, and there seems to be evidence that there is a chemical property to urticating hairs in addition to physical properties.
[edit] Sexual dimorphism
Some tarantula species exhibit pronounced sexual dimorphism. Males tend to be smaller (especially the abdomen) and may be quite colorful, as in the very large Bolivian and Peruvian species Pamphobeteus antinous, in which the female is dark brown and the male shiny iridescent purple. Most species are not sexually dimorphic. There are many urban legends about being able to sex tarantulas by look alone, but unless the male has matured or it is sexually dimorphic before a male's ultimate (maturing) molt, the sex cannot be determined by look alone.
A non-matured male can be sexed by looking at a cast exuvium for exiandrous fusillae or a spermathecae. Ventral sexing is less reliable but if done correctly, it is relatively reliable. Males have much shorter lifespans than females because they die relatively soon after maturing. Few live long enough for a post-ultimate molt. It is unlikely that it happens much in natural habitat because they are vulnerable, but it has happened in captivity, although rare. Most males do not live through this molt as they tend to get their emboli (mature male sexual organs on pedipalps) stuck in the molt. Most tarantulas kept as pets are desired to be female. Wild caught tarantulas are often mature males because they wander out in the open and are more likely to be caught while females are in burrows. A tarantula huddle up in the corner with its legs tucked close to it, that doesn't react, or reacts slowly to touch, is stressed. A dying tarantula will curl its legs like a clutched hand under it. Its movement is hydraulically motivated and an extended leg takes more energy than a curled one. If a tarantula does this, it needs to go into some sort of small environment such as a small tupperware with water (either on a towelette or a water bowl) and be put in the dark for a few days. Tarantulas do not die on their backs unless there is trouble molting.
Excessive dryness can kill tarantulas, especially tropical tarantulas. Although higher humidity helps with molting, it appears that for many tarantulas, humidity does not highly affect molting as much as the actual hydration of the tarantula prior to molting. Most notably though, Theraphosa species must be high in humidity to molt. All tarantulas require a water dish.
[edit] Ecology
Tarantulas are nocturnal predators, killing their prey by injecting venom through their fangs. The hungry tarantula typically waits partially hidden at the entrance to its retreat to ambush passing prey. It has sensitive hairs that enable it to detect the size and location of potential victims from the vibrations caused by their movements. Some species also use their silk fiber to detect motion (when prey triggers a line). Like many other spiders, it cannot see much more than light, darkness, and movement (see spiders for more about their eyesight), and uses its sense of touch to perceive the world around it. That being said, they are anything but sloppy or imprecise about the way they capture their prey. They generally seem to choose prey on the basis of how dangerous it is perceived to be, the general size of the potential prey animal, etc. Some tarantulas succeed in occasionally capturing small birds, small lizards, small snakes, small mammals such as mice, and even small fish, but their ordinary prey consists of insects such as crickets (for ground dwellers) and moths (for arboreal species).[4]
[edit] Life cycle
[edit] Ecdysis
Like other spiders, tarantulas have to shed their exoskeleton periodically in order to grow, a process called molting. Young tarantulas may do this several times a year as a part of their maturation process, while full grown specimens will only molt once every year or so, or sooner in order to replace lost limbs or lost urticating hairs[citation needed].
Tarantulas may live for many years--most species taking 2 to 5 years to reach adulthood, but some species may take up to 10 years to reach full maturity. Upon reaching adulthood, males typically have but a 1 to 1.5 year period left to live and will immediately go in search of a female with which to mate. It is rare that upon reaching adulthood the male tarantula will molt again.
The habit of male spiders wandering in search of mates makes them especially visible. In late summer and early autumn (September and October in the northern hemisphere), the males will leave their hiding places and walk about, hoping to encounter the hiding place of a female with which to mate. They are willing to cross roads and trails in this quest, and that is when they are most likely to be observed.
When the mature male encounters the burrow of a female, he will draw the female out and signal his intentions to mate by vibrating his body and tapping his front legs. If the female is receptive to mating, she will also vibrate and tap her legs. After mating, the male must get away quickly, or it is possible that he will be eaten. A female tarantula who is unreceptive to mating may also eat the male if he attempts to mate. This result, however, is less common among tarantulas than other spiders. Certain species of tarantulas have been known to mate multiple times over the course of several weeks.
Since females will continue to molt after reaching maturity, they are able to regenerate lost limbs. Female specimens have been known to reach 30 to 40 years of age, and have survived on water alone for up to 2.5 years. Grammostola rosea spiders are renowned for going for long periods without eating.
[edit] Reproduction
As with other spiders, the mechanics of intercourse are quite different from those of mammals. Once a male spider reaches maturity and becomes motivated to mate, it will weave a web mat on a flat surface. The spider will then rub its abdomen on the surface of this mat and in so doing release a quantity of semen. It may then insert its pedipalps (short leg-like appendages between the chelicerae and front legs) into the pool of semen. The pedipalps absorb the semen and keep it viable until a mate can be found. When a male spider detects the presence of a female, the two exchange signals to establish that they are of the same species. These signals may also lull the female into a receptive state. If the female is receptive then the male approaches her and inserts his pedipalps into an opening in the lower surface of her abdomen. After the semen has been transferred to the receptive female's body, the male will generally quickly leave the scene before the female recovers her appetite.
Females deposit 50 to 2000 eggs, depending on the species, in a silken egg sac and guard it for 6 to 7 weeks. The young spiderlings remain in the nest for some time after hatching where they live off the remains of their yolk sac before dispersing.
Tarantulas usually live in solitude and, being cannibalistic, will attack and eat others of their own kind. There are however, exceptions such as the pinktoe tarantula (Avicularia avicularia), which can be kept communally, as members of this species are more tolerant of each other. If the vivarium is big enough, has enough hiding spots, and the specimens are about the same size and well fed, there should be little or no cannibalism. However, keeping tarantulas communally is not recommended and should not be attempted except by experienced keepers.
[edit] Taxonomy
The family Theraphosidae is divided up into 12 subfamilies, containing over 100 genera and around 900 species between them.
- Acanthopelminae, first described by Frederick Octavius Pickard-Cambridge in 1897, is a subfamily of small, terrestrial New World tarantulas. This subfamily has only one genus, Acanthopelma, and two species, A. beccarri and A. rufescens, found in Guyana and Central America.
- Aviculariinae are a subfamily of tropical, tree-dwelling New World tarantulas. They range from the Caribbean to South America, and are commonly known as "pinktoe" tarantulas. The genera Avicularia, Ephebopus and Pachistopelma possess urticating hairs, but cannot "flick" them into the air; instead the hairs are pressed into an enemy upon contact.
- Eumenophorinae are a subfamily of old-world tarantulas, mostly from Africa and surrounding regions. In addition, some authors place genus Proshapalopus (a genus found in Brazil, and not in Africa) in this sub-family.
- Harpactirinae are a group of old-world tarantulas from Africa, though smaller than Eumenophorinae. They are known as baboon spiders for their hairy legs and the thick black scorpulae at the end of their feet, which are said to resemble baboons.
- Ischnocolinae contains spiders from around the world.
- The earth tigers of subfamily Ornithoctoninae are a group of old-world tarantulas which are found primarily in Southeast Asia, southern China, and Borneo. This group includes the infamous Chinese bird spider, and species in this sub-family are known for being ill-tempered.
- Poecilotheriinae are tree spiders from India and Sri Lanka, some of which are considered Template:Endangered species. This subfamily contains only a single genus.
- Selenocosmiinae is a subfamily which consists mainly of tarantulas from East Asia and Australia. Like the East Asian tarantulas in Ornithoctoninae, these are known for their strong venom and defensive disposition. The genera Psalmopoeus and Tapinauchenius do not have urticating hairs, unusual among New World species.
- Selenogyrinae consists of tarantulas from India and Africa.
- Stromatopelminae are tree-dwelling tarantulas from western Africa.
- Theraphosinae consists of new-world terrestrial tarantulas with urticating hairs. The majority of spiders kept as pets are of this sub-family.
- Thrigmopoeinae are Indian tarantulas.
A few genera are presently not well-classified, and/or have classifications which are disputed, including Brachionopus, Cardiopelma and Proshapalopus
[edit] Human society
Because of their large size, tarantulas are noticed and utilized by humans in ways which other spiders generally are not.
[edit] Pets
Tarantulas can be kept as pets and are considered good "apartment pets" by many, being quiet animals, requiring surprisingly little maintenance or cleaning, since unlike snakes and lizards they have no detectable odor. Because of their docile behavior, the species most commonly kept as pets are the Chilean rose tarantula (Grammostola rosea), for their price and the Mexican redknee tarantula (Brachypelma smithi), for their beauty. These two species are also some of the easier to care for and are usually easy to handle, while other species (Including most Asian species, such as the cobalt blue tarantula ) are more aggressive and shouldn't be handled. Some of the more docile types seem to have a habit of relaxing in people's hands, perhaps attracted by the warmth.
Tarantulas make quite inexpensive pets. Most species can be purchased as juveniles for $20-$50 USD. Adults can be quite expensive as they approach breeding age, and adults of many species can easily reach the several hundred US dollar range. Housing for most species can cost another 40 USD.
A terrarium with an inch or two of damp ground coconut fiber, or a mixture of soil and sphagnum moss (but not with cedar shavings as they are toxic to many spiders) on bottom provides an ideal habitat. (Burrowing tarantulas will require a much deeper layer.) Ambient temperature and humidity vary by species, with most thriving between 75 degrees and 80°F (24 to 27°C) and between 40% and 80% humidity.
Tarantulas can be fed a variety of living animals (insects, small mice or Pinky Mice, and small fish in the water bowl, are some of the foods tarantulas eat). Tarantulas should not be fed vertebrates on a regular basis as the calcium in the bones will cause complications during molting and may kill the tarantula. A tropical roach colony is a good way to maintain a food supply for a number of tarantulas. The discoid cockroach and death's head cockroach in particular are very easy to care for and will not infest your home if they escape. The death's head cockroaches can be kept in an aquarium with no lid since they cannot climb glass and don't fly. Maintaining a colony of death's head cockroaches only requires keeping them in the dark, feeding them a handful of dog food every couple of weeks and misting them with water every day or two.
Other tarantulas that may make interesting pets are the Brazilian (or "giant") whiteknee, Chaco golden knee, and Brazilian salmon pink birdeater. These are three of the larger species, each growing over 8 inches with the Brazilian birdeater sometimes reaching 10 inches and considered by many to be the largest species that is docile enough to handle. The foregoing are terrestrial tarantulas, i.e., they generally live in burrows or natural shelters near the ground. Arboreal tarantulas require different housing since, when adult, they make webbed shelters well above ground. Those include Avicularia avicularia and Avicularia metallica, which are generally quite calm and rarely bite. (Any spider will bite if it is being hurt or put in fear for its life.) The arboreal spiders can have large legspans, but their bodies are much less massive than the typical terrestrial tarantulas.
[edit] Consumption
On one of their TV specials, National Geographic illustrated the methods used by some Amazonian peoples to hunt and cook tarantulas. A tarantula was captured by holding it down with a stick and its legs were then bent upward and bound together. The creature was then roasted alive in a folded leaf. On that show, the American participant tasted the meat and commented that it reminded him of shrimp. The Goliath birdeater tarantula (Theraphosa Blondi) is considered a delicacy by the indigenous Piaroa of Venezuela. Another appearance of the tarantula as food was made on Anthony Bourdain's A Cook's Tour. Fried tarantulas are also considered a delicacy in Cambodia.[5]
[edit] Bites
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.
[edit] First aid
Encourage bleeding to wash out the puncture wounds from within, then clean the bite site with soap and water and protect it against infection. As with other puncture wounds, antiseptics may be of limited use since they may not penetrate to the full depth of a septic wound, so wounds should be monitored for heat, redness, or other signs of infection. Skin exposures to the urticating hairs can be treated by applying and then pulling off some sticky tape such as duct tape, which carries the hairs off with it.
If any breathing difficulty or chest pain occurs, go to a hospital as this may indicate an anaphylactic reaction. As with bee stings, the allergic reaction may be many times more dangerous than the toxic effects of the venom. If this occurs an EpiPen (an autoinjector of epinephrine, also known as adrenaline) should be administered as soon as possible, as complete airway blockage can occur within 20 minutes of exposure to the allergen, depending on the severity of the allergy.
[edit] Etymology
The word tarantula applies to several very different kinds of spider. The spider originally bearing that name is one of the wolf spiders, Lycosa tarantula, found in the region surrounding the city of Taranto (or Tarentum in Latin), a town in Southern Italy. Compared to true tarantulas, wolf spiders are not particularly large or hairy.
The bite of L. tarantula was once believed to cause a fatal condition called tarantism, whose cure was believed to involve wild dancing of a kind that has come to be identified with the tarantella. However, modern research has shown that the bite of L. tarantula is not dangerous to human beings. There appears to have existed a different species of spider in the fields around Taranto responsible for fairly severe bites. The likely candidate (and the only spider found in the area which is dangerous to man) is the malmignatte or Mediterranean black widow. This spider, which belongs in the genus Latrodectus, is a close relative of the black widow and red-back spiders, and has a bite which is medically significant. However, the so-called tarantulas were fairly large, frequently visible (as is typical of wolf spiders), and thus drew more attention. These factors, combined with the belief in the fatality of tarantism, assured the other kind of spiders generally called tarantulas a fearsome reputation.
When theraphosidae were encountered by European explorers in the Americas, they were named "tarantulas". Nevertheless, these spiders belong to the suborder Mygalomorphae, and are not at all closely related to wolf spiders.
The name "tarantula" is also applied to other large-bodied spiders, including the purseweb spiders or atypical tarantulas, the funnel-web tarantulas (Dipluridae and Hexathelidae), and the dwarf tarantulas. These spiders are related to true tarantulas (all being mygalomorphs), but are classified in different families. Huntsman spiders of the family Sparassidae are also informally referred to as "tarantulas" because of their large size. They are not related, belonging to the suborder Araneomorphae.
[edit] Popular culture
- The word "Ferrantelli" is synonymous with Tarantula in Italian.
- The 1955 film Tarantula, one of the many 1950s "big bug" science fiction films, featured a tarantula grown to gigantic size due to atomic-age nutrients.
- The 1958 film Earth vs. the Spider (loosely remade in 2000) also features a gigantic spider terrorizing the countryside.
- In a Far Side comic, Gary Larson used his typical combination of two or more unrelated ideas: a family of giant spiders driving a car, with a bumper sticker containing a "Have a Nice Day" smiley face - with eight eyes.
- The Beast Wars character Tarantulas transformed into a Giant Tarantula, and later into a Metal Tarantula.
- The 1990 film Arachnophobia featured a Tarantula as the 'queen'.
- The villain in the film Wild Wild West uses a giant mechanical spider based on a Tarantula. Furthermore, the heroes' plan to assault it is inspired by watching a Tarantula hawk wasp attack a real Tarantula.
- The 1990 film Home Alone featured a pet tarantula in various scenes.
- The first single from the 2007 album Zeitgeist by The Smashing Pumpkins is titled "Tarantula".
- In the television show Star Trek: The Next Generation it is revealed that transport chief Miles O'Brien keeps a tarantula named Christina as a pet.
- In City of Villains, Tarantulas are spider-like mechs used by Arachnos
- The leader of the spiders in Eight Legged Freaks is a giant tarantula.
- Tarantulas are occasionally mentioned on the TV show Red Dwarf, as being a phobia of a couple of the characters, including one famous scene where one of them thinks a tarantula is crawling around in his lap, but it's in fact an android's detached hand.
- In Mighty Morphin Power Rangers, Zack Taylor was scared of Tarantula.