Amblypygi

Taken in Singapore forest at night.

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Amblypygi is an order of invertebrate animals belonging to the class Arachnida, in the subphylum Chelicerata of the phylum Arthropoda. They form a separate order of arachnids alongside the spiders, scorpions and others.

Amblypygids are also known as whip spiders and tailless whip scorpions (not to be confused with whip scorpions that belong to the Arachnid order Thelyphonida). The name "amblypygid" means "blunt rump", a reference to a lack of the telson ("tail") carried by related species. Despite an offputting appearance, they are harmless to humans.

By 2003, 5 families, 17 genera and around 155 species had been discovered. They are found in tropical and subtropical regions worldwide. Some species are subterranean; many are nocturnal. During the day, they may hide under logs, bark, stones, or leaves. They prefer a humid environment.

Amblypygids range from 4 to 10 inches (10 to 25 cm) in size, including legspan. Their bodies are broad and highly flattened, with a solid carapace and a segmented abdomen. They have a pair of median eyes at the front of the carapace, located just above the chelicerae in a manner somewhat similar to crustaceans, and three smaller eyes placed further back on each side, for eight eyes in total.

Amblipygids possess medium to poor eyesight, however their pedipalps, which serve as sensors for many akin arachnids, are modified and inward-adapted for grabbing and retaining prey, much like those of a praying mantis.[5] The first pair of legs are also modified and act as sensory organs, while the animal uses the other six legs for walking. The sensory legs are very thin, have numerous sensory receptors, and can extend several times the length of body. Typically, the animal holds one of these legs out in front of it as it moves, and uses the other to probe the terrain to the side.[5]

Amblypygids possess no silk glands or venomous fangs, however their chelicerae do eject a digestive acidic enzyme, unlike those of sun spiders, for example. They rarely bite if threatened, but can grab fingers with pedipalps, resulting in thorn-like puncture injury.