Amblypygi are a nocturnal group of arachnids, commonly called whip spiders or tailless whip scorpions (not to be confused with spiders in the order Araneae or whip scorpions, also called vinegaroons, that belong to the related order Thelyphonida). The name "amblypygid" means "blunt tail", a reference to a lack of the flagellum that is otherwise seen in whip scorpions. Amblypygids have dorsoventrally flattened bodies, two pairs of book lungs and long thin legs where only the rear three pairs of legs are ambulatory. The anterior first pair of legs are very thin, highly segmented and flexible (like a whip) and are covered in many different sensory receptors. Thus, these legs are called antenniform legs, and mainly function similarly to the antennae of insects. Amblypygids also have spiny, raptorial pedipalps that are used for defense and to capture prey. Amblypygids possess no silk glands or venomous fangs and are harmless to humans.
Amblypygids can live around 5-10 years and are found in warm tropical and subtropical regions worldwide. They seek refuge during the day in crevices of trees, rocky outcroppings or cliff banks, underneath rocks or bark, and come out at night to be active. Some species are subterranean and dwell in caves. Most species of amblypygids have eight eyes, while a few species that live in caves have reduced or no eyes.
As of 2020, there are 5 extant families, 17 genera and over 210 species of Amblypygi that have been described. Fossilized amblypygids have been found dating back to the Carboniferous period, such as the extinct genus Graeophonus (315-305 million years ago).