Tarantulas are among the largest spiders in the world, constituting the family Theraphosidae. They are characterized by notably hairy bodies and legs, a sight that often freaks people out. However, despite such an intimidating appearance, tarantulas are solitary and remain hidden in underground burrows for most parts of the day. At night, they stealthily wait for their prey to approach them. Once in range, these spiders lunge forward and bite the prey with their fangs, releasing venom to incapacitate the prey.
Scientific Classification
Animalia
Arthropoda
Arachnida
Araneae
Theraphosidae
Scientific Classification
Animalia
Arthropoda
Arachnida
Araneae
Theraphosidae
Typically brown, some tarantula species also exist in shades of blue, green, orange, and yellow. These spiders are found on all continents except Antarctica. Since tarantulas do not typically bite humans unless disturbed, they have been mindlessly collected for the pet trade. As a result, they are currently protected by the Convention on International Trade in Endangered Species (CITES).
List of Common Tarantula Species
As of June 2025, around 1,130 species of tarantulas have been identified in the World Spider Catalog. Some of the most commonly found species of the New and the Old World are listed below.
Size: Length: Body: 2 to 4.5 in (5 to 11 cm); Legspan: 3 to 12 in (8 to 30 cm)
The largest species by length, the Goliath birdeater (Theraphosa blondi), measures up to 5.1 in (13 cm).
Tarantula
In most tarantula species, the males are smaller (and lighter, too) than the females since they mature relatively early compared to the females.
Weight: 1 to 3 oz (28.3 to 85 g). The Goliath birdeater is also the heaviest of all species, and it can weigh up to 6.2 oz (175 g).
Body and Coloration: As members of the class Arachnida, tarantulas have two main body parts:the prosoma (or cephalothorax)and the opisthosoma (or abdomen). The two parts are connected by a waist-like piece called the pedicel or pregenital somite, which allows the opisthosoma to move relative to the prosoma.
The prosoma bears a pair of two-segmented appendages called chelicerae, which are located just below the eyes. These appendages contain venom glands, which open through hollow fangs. The fangs can extend downward and outward just before a bite and can fold back when not in use.
A pair of six-segmented appendages called pedipalps lie next to the mouth. In both sexes, these appendages help in handling food and sensory input. In most species, the pedipalps contain sharp, jagged plates, which help crush the captured prey. As with other male spiders, in male tarantulas, too, these appendages are modified to function as sperm transfer organs.
There are four pairs of walking legs in the prosoma, with each leg having seven segments. These segments, from the base to the tip, are the coxa, trochanter, femur, patella, tibia, tarsus, and pretarsus. At the tip of these legs are 2 to 3 retractable claws that help in better gripping.
The opisthosoma houses the internal organs and tubular silk-producing organs called spinnerets. These organs, usually 2 to 4 in tarantulas, are internally connected to silk glands.
The tarantulas found in North America are typically brown, but those found in other continents may exhibit other shades as well. For instance, the cobalt blue tarantula is blue, while the striped-knee tarantula is black with white stripes. The greenbottle blue tarantula, on the other hand, has a green prosoma and orange opisthosoma.
All tarantulas have thick, hair-like bristles called setae covering their bodies and legs. These bristles are sensory in function and help detect vibrations from air or ground.
Tarantula Claws
Tarantula Eyes
Organ Systems
The digestive system begins with a straw-shaped mouth located under the chelicerae. It is followed by a digestive tube that runs the entire length of the body. In the prosoma, this tube expands into a sucking stomach and continues into the opisthosoma, where it forms the intestines. The intestines end in the hindgut and anus, from where waste is expelled.
Tarantulas have a long, tubular heart located along the dorsal side of the opisthosoma. The heart is neurogenic (controlled by nerves and not muscles) and pumps body fluid (hemolymph) through an open circulatory system, using sinuses instead of blood vessels.
They have two pairs of book lungs for respiration. While the first pair is situated near the front of the abdomen, the second pair lies farther back. Each book lung consists of 15 or more thin, layered plates of folded tissue resembling a book (hence the name). These folds have numerous blood vessels that allow gaseous exchange between the air and the hemolymph.
These spiders typically sense their surroundings using their setae. They also have eight eyes like most spiders, but their vision is poor and limited to the detection of light, shadows, and motion.
Distribution
These spiders are found in warm regions of all continents except Antarctica. They occur throughout South America, Central America, the United States, and Mexico. Their range also extends to Africa, Australia, and much of Asia, including the Ryukyu Islands and Japan.
Tarantulas are found in several European countries, too, including Spain, Portugal, Turkey, Italy, and Cyprus.
Habitat
Tarantulas usually inhabit rainforests, deserts, grasslands, and scrublands. They prefer living in underground burrows, though some may also live on the ground under rocks and tree logs. A few species, like the ornate tiger spider (Poecilotheria ornata), are arboreal and live in trees.
Tarantula Habitat
Tarantula Spider
Diet
They feed on large insects and other arthropods, like centipedes, millipedes, and even other spiders. Some large tarantula species may occasionally consume small vertebrates, including lizards, frogs, mice, bats, birds, and small snakes.
Behavior
Typically active at night, tarantulas are ambush predators, meaning they remain hidden, motionless in their burrows, and do not actively chase their prey. Instead, when the prey comes within striking distance, the tarantula lunges forward and pins the prey down with its legs.
Before attacking the prey, a tarantula may display a ‘threat posture’ by raising its prosoma and lifting its front legs into the air. It may then extend and spread its fangs, getting ready for a bite. Some species, like the Goliath birdeater, produce a hissing sound by rubbing their appendages (stridulation).
The tarantula uses its chelicerae and fangs to bite the prey, delivering venom into its body. The venom immobilizes the prey in a few minutes and begins to break down the body tissues of the prey, making it ready for digestion.
These spiders walk in a diagonal gait, in which the first and third legs on one side move in sync with the second and fourth legs on the other side.
Arboreal tarantulas build tent-like residential structures by spinning silk, while terrestrial species usually line their burrows with silk to reinforce the walls.
Lifespan
The lifespan of male and female tarantulas varies considerably. While females survive 10 to 25 years in the wild, males have an average lifespan of only 3 to 7 years since they die shortly after mating. In captivity, females of some species, like the Texas brown tarantula (Aphonopelma hentzi), have been found to survive for as many as 40 years.
Reproduction and Life Cycle
On reaching sexual maturity, a male tarantula starts weaving a small, hammock-like sperm web or web mat. He then rubs his abdomen on this web, releasing the semen on it. To keep the semen viable until a female is found, the male inserts his pedipalps into the pool of semen. On detecting a probable partner, the male and the female tarantulas exchange signals about each other’s receptivity. If the female is sexually receptive, the male approaches her, inserts his pedipalps into an opening in the lower surface of her abdomen, and transfers the semen to her body. Having mated, the male quickly leaves the site since the female may become aggressive after mating.
The female deposits between 50 and 2,000 eggs, depending on the species. These eggs are laid in a silken egg sac and guarded by the female for 6 to 8 weeks. In most species, the females frequently rotate or turn the egg sac using their pedipalps and legs (brooding) to prevent deformation from remaining in one position too long. The eggs hatch within the sac, and the spiderlings emerge. These spiderlings remain in the mother’s burrow and live off the remains of their yolk sacs without consuming food from an external source.
Young tarantulas shed their exoskeleton (molt) multiple times every year as a part of their maturation process. Adults molt, too, though their frequency is once a year or less, typically to replace lost limbs or lost urticating hairs.
While male tarantulas typically attain sexual maturity in 2 to 5 years, females take longer, often maturing in 8 to 10 years. Once mature, the males usually stop molting, focus on mating, and typically die in a year. The females, on the other hand, continue to molt even after attaining maturity.
Tarantula Spiderlings
Tarantula Photos
Predators
Spider wasps, or tarantula wasps (family Pompilidae), specialize in hunting and feeding on tarantulas. Other arthropods, such as giant centipedes and scorpions, are also known to prey on them.
Several vertebrates, including lizards, snakes, frogs, and birds, also consume tarantulas. Additionally, some mammals that are immune to the tarantula venom, such as coati, kinkajou, opossums, mongooses, and the honey badger, can also feed on them.
Adaptations
In addition to body hair, most New World tarantulas, like those in the genus Avicularia, possess specialized setae called urticating hairs in the abdomen. They typically kick these hairs off at their predators using their hind legs. These hairs are barbed and irritate the predators, sometimes even causing death. If inhaled by humans, these bristles cause itching, rashes, or respiratory issues. The urticating hairs are absent in Old World tarantulas.
