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Overview of Tarantulas

Tarantulas are large and often hairy spiders of the family Theraphosidae.
There are 1,040 identified species, with 156 genera.
The term "tarantula" is used for members of the family Theraphosidae, as well as other members of the same infraorder (Mygalomorphae).
Some of the more common species are popular in the exotic pet trade.
Tarantulas have an exoskeleton for muscular support and a body comprising two main parts: the prosoma and the opisthosoma.
Tarantulas range in size from 5 to 11 cm in body length and 8-30 cm in leg span.
Tarantulas have various natural habitats, including savanna, grassland, rainforest, desert, and mountains.
Tarantulas are becoming more popular as pets and are readily available in captivity.
Tarantulas can be identified by their urticating hairs, size, downward-facing fangs, and possession of two book lungs.
Tarantulas occur throughout the Americas, Africa, Asia, and Australia.
Tarantulas are ambush predators that mainly eat large insects and other arthropods, but sometimes kill and consume small vertebrates.
Tarantulas have eight legs, two chelicerae with fangs, two six-segmented pedipalps, and either two or four spinnerets.Tarantulas: Anatomy, Predators, Bites, Sexual Dimorphism, Life Cycle and Reproduction

Anatomy:

Tarantulas have two sets of book lungs for breathing, located in the abdomen
Tarantula blood is not true blood, but rather a liquid called hemolymph
Tarantulas have urticating hairs on their abdomens, which they use as protection against enemies
All tarantulas are venomous

Predators:

Tarantulas are prey for many other animals, including wasps, scorpions, centipedes, lizards, birds, snakes, and mammals
Some mammals, such as coatis, kinkajous, opossums, mongooses, and honey badgers, are immune to the venom of tarantulas
Humans consume tarantulas for food in their native ranges

Bites and Urticating Bristles:

Tarantula bites cause serious discomfort that might persist for several days, but are generally not deadly to humans
Tarantulas may signal their intention to attack by rearing up into a "threat posture"
New-world tarantulas have urticating hairs on their abdomens, while Old-world tarantulas do not

Sexual Dimorphism:

Males tend to be smaller and may be dull in color when compared to their female counterparts
Males typically have longer legs than females
Females possess spermathecae, except for a few species, while males have epiandrous fusillae

Life Cycle:

Tarantulas shed their exoskeleton periodically as they grow, a process called molting
Most tarantula species take between two and five years to reach sexual maturity
Females mate and lay eggs once per year, while males typically have an 18-month period left to live after reaching adulthood

Reproduction:

Males weave a web mat on a flat surface and release semen onto it
If a female is receptive, then the male approaches her and inserts his pedipalps into an opening in the lower surface of her abdomen.Reproduction and Taxonomy of Tarantulas
After mating, the male tarantula leaves the female's body quickly, and the female deposits 50 to 2,000 eggs, depending on the species, in a silken egg sac and guards it for six to eight weeks.
Females turn the egg sac often to keep 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.
Linnaeus initially placed all spiders in a single genus, Aranea, but in 1802, Charles Athanase Walckenaer separated mygalomorph spiders into a separate genus, Mygale, leaving all other spiders in Aranea.
In 1869, Tamerlan Thorell used the family name "Theraphosoidae" for the mygalomorph spiders known to him, rather than "Mygalidae."
A 2019 phylogenomic study recognized 12 subfamilies, and the relationship between the subfamilies found in the study is shown in a cladogram.
All species that possess urticating hairs and have been seen to use them in bombardment behavior are placed in the "bombardier clade."
It is not clear whether the possession of urticating hairs was an ancestral trait of the clade or whether it represents multiple gains.
The World Spider Catalog accepted 121 genera of tarantulas as of February 2023.
Fossils of mygalomorph spiders date back to the Triassic, but only two specimens have been found so far, which can be convincingly assigned to the Theraphosidae.
One is from Dominican Republic amber, and the other is from Chiapas (Mexico) amber, and both are about 16 million years old.
Tarantulas are unique in their brooding behavior, egg sac construction, and the size of their young.