Tarantula facts for kids
Quick facts for kids Tarantula |
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| Mexican pink tarantula, Brachypelma klaasi | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Class: | Arachnida |
| Order: | Araneae |
| Infraorder: | Mygalomorphae |
| Clade: | Avicularioidea |
| Family: | Theraphosidae Thorell, 1869 |
| Diversity | |
| 148 genera, 1,236 species | |
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Tarantulas are large and often hairy spiders of the family Theraphosidae. As of August 2022[update], 1,040 species have been identified, with 156 genera.
Some of the more common species have become popular in the exotic pet trade. Many New World species kept as pets have setae known as urticating hairs that can cause irritation to the skin, and in extreme cases, cause damage to the eyes.
Contents
Overview
The tarantula is an invertebrate that relies on an exoskeleton for muscular support.
Tarantula sizes can range from as small as the size of a BB pellet to as large as a dinner plate when the legs are fully extended. Depending on the species, the body length of tarantulas ranges from about 5 to 11 cm (2 to 4+1⁄2 in), with leg spans of 8–30 cm (3–12 in). 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 oz) 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 4 cm (1+1⁄2 in).
T. blondi is generally thought to be the heaviest tarantula, and T. apophysis has the greatest leg span. Two other species, Lasiodora parahybana (the Brazilian salmon birdeater) and Lasiodora klugi, rival the size of the two goliath spiders.
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.
Etymology
The spider originally bearing the name tarantula was Lycosa tarantula, a species of wolf spider native to Mediterranean Europe. The name is derived from the southern Italian town of Taranto. The term tarantula was subsequently applied to almost any large, unfamiliar species of ground-dwelling spider.
Distribution
Tarantulas of various species occur throughout the United States, Mexico, in Central America, and throughout South America. Other species occur variously throughout Africa, much of Asia (including the Ryukyu Islands in southern Japan), and all of Australia. In Europe, some species occur in Spain, Portugal, Turkey, southern Italy, and Cyprus.
Habits
Some genera of tarantulas hunt prey primarily in trees; others hunt on or near the ground. All tarantulas can produce silk. Arboreal species typically reside in a silken "tube tent". terrestrial species line their burrows with silk to stabilize the burrow wall and facilitate climbing up and down.
Tarantulas mainly eat large insects and other arthropods such as centipedes, millipedes, and other spiders, using ambush as their primary method of prey capture. Armed with their massive, powerful chelicerae tipped with long, chitinous fangs, tarantulas are well-adapted to killing other large arthropods. The biggest tarantulas sometimes kill and consume small vertebrates such as lizards, mice, bats, birds, and small snakes.
Appendages
A tarantula has four pairs of legs and two additional pairs of 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 at the end of each leg are used to grip surfaces for climbing. Also on the end of each leg, surrounding the claws, is a group of bristles, called the scopula, which help the tarantula to grip better when climbing surfaces such as glass. The fifth pair is the pedipalps, which aid in feeling, gripping prey, and mating in the case of a mature male. The sixth pair of appendages is the chelicerae and their attached fangs. When walking, a tarantula's first and third legs on one side move at the same time as the second and fourth legs on the other side of its 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 haemolymph entering the leg.
Tarantulas, like almost all other spiders, have their primary spinnerets at the end of the opisthosoma. Unlike most spider species in the infraorder Araneomorphae, which includes the majority of extant spider species, and most of which have six, tarantula species have two or four spinnerets. Spinnerets are flexible, tube-like 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 100 spinning tubes through which silk is exuded. As the silk is pulled out of the spinnerets, the shear forces cause proteins in the silk to crystallize, transforming it from a liquid to a solid thread.
Digestive system
The tarantula's mouth is located on the lower front part of its prosoma. The mouth is a short, straw-shaped opening that can only suck. 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 coating the prey with digestive juices secreted from openings in the chelicerae.
The tarantula's digestive organ (stomach) is a tube that runs the length of its body. Once the liquefied food enters the intestines, it is broken down into particles small enough to pass through the intestine walls into the hemolymph (blood stream), where it is distributed throughout the body. After feeding, the leftovers are formed into a small ball by the tarantula and thrown away. In a terrarium, they often put them into the same corner.
Nervous system
A tarantula's central nervous system (brain) is located in the bottom of the inner prosoma. Although a tarantula has eight eyes like most spiders, in hunting, it primarily depends on vibrations given off by the movements of its prey. A tarantula's setae are very sensitive organs and are used to sense chemical signatures, vibrations, wind direction, and possibly even sound. Tarantulas are also very responsive to the presence of certain chemicals such as pheromones.
The eyes 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 generally have better vision compared with terrestrial tarantulas.
Respiratory system
All types of tarantulas have two sets of book lungs (breathing organs); the first pair is located in a cavity inside the lower front part of the abdomen near where the abdomen connects to the cephalothorax, and the second pair is slightly farther back on 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 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.
Circulatory system
A tarantula's blood is unique (not only in appearance). A tarantula's blood is not true blood, but rather a liquid called hemolymph (or haemolymph). At least four types of hemocytes, or hemolymph cells, are known.
If the exoskeleton is breached, loss of hemolymph will kill the spider unless the wound is small enough that the hemolymph can dry and close it.
Predators
Despite their large size and fearsome appearance and reputation, tarantulas themselves are prey for many other animals. The most specialized of these predators are large members of the wasp family Pompilidae such as the wasp Hemipepsis ustulata. These wasps are called "tarantula hawks".
Tarantulas are also preyed upon by a wide variety of vertebrates. Many of these, including lizards, frogs, birds, snakes and mammals, are generalist predators of all kinds of large arthropods. Mammals that have been known to prey on tarantulas, such as the coati, kinkajou, and opossum in the New World, and mongooses and the honey badger in the Old World, are often immune to the venom of their arthropod prey.
Humans also consume tarantulas for food in their native ranges. They are considered a delicacy in certain cultures (e.g. Venezuela and Cambodia). They can be roasted over an open fire to remove the bristles (described further below) and then eaten.
Bites and urticating bristles
All tarantulas are venomous. Although their venom is not deadly to humans, some bites cause serious discomfort that might persist for several days. In general, the effects of the bites of all kinds of tarantula 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 and to produce intense spasms that may recur over a period of several days. The venom of the African tarantula Pelinobius muticus also causes strong hallucinations.
Before biting, a tarantula may signal its intention to attack by rearing up into a "threat posture", which may involve raising its prosoma and lifting its front legs into the air, spreading and extending its fangs, and (in certain species) making a loud hissing by stridulating. Tarantulas often hold this position for longer than the duration of the original threat. Their next step, without biting, may be to slap down on the intruder with their raised front legs. If that response fails to deter the attacker, the tarantulas of the Americas may next turn away and flick urticating hairs toward the pursuing predator. The next response may be to leave the scene entirely, but especially if no line of retreat is available, their final response may also be to whirl suddenly and bite. Some tarantulas are well known to give "dry bites", i.e., they may defensively bite some animal that intrudes on their space and threatens them, but they do not pump venom into the wound.
Life cycle
Like other spiders, tarantulas have to shed their exoskeleton periodically as they grow, a process called molting. A young tarantula may do this several times a year as a part of the maturation process, while full-grown specimens only molt once a year or less, or sooner, to replace lost limbs or lost urticating hairs. It is visibly apparent that molting is imminent when the exoskeleton takes on a darker shade. If a tarantula previously used its urticating hairs, the bald patch turns from a peach color to deep blue. The tarantula also stops feeding and becomes more lethargic during this time.
While most Tarantulas species take between two to five years to reach maturity, some species can take up to 10 years. Upon reaching adulthood, males typically have an 18-month period left to live so immediately go in search of a female mate. Although females continue to molt after reaching maturity, male rarely do again once they reach adulthood. Those that do often can become stuck during the molting process and die.
Female can live for 30 to 40 years. Grammostola rosea spiders, which eat once or twice a week, have lived up to 20 years in captivity. Some have survived on water alone for up to two years.
Reproduction
After reaching maturity, a female tarantula normally mates and lays eggs once per year, although they do not always do so.
Females deposit 50 to 2,000 eggs, depending on the species, in a silken egg sac and guard it for six to eight weeks. During this time, the females stay very close to the egg sacs and become more aggressive. Within most species, the females turn the egg sac often, which is called brooding. This keeps the eggs from deforming due to sitting in one position too long. The young spiderlings remain in the nest for some time after hatching, where they live off the remains of their yolk sacs before dispersing.
Fossil record
Although fossils of mygalomorph spiders date back to the Triassic, only two specimens have been found so far which can be convincingly assigned to the Theraphosidae. One is from Dominican Republic amber; the other is from Chiapas (Mexico) amber. Both these ambers are quite young, being Miocene in age or about 16 million years old.
See also
In Spanish: Terafósidos para niños
