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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.