| Amblypygi Temporal range: Upper Carboniferous–Recent |
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| Damon diadema | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Arachnida |
| Order: | Amblypygi Thorell, 1883 |
| Families | |
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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 totally harmless to humans.[1][2]
By 2003, 5 families, 17 genera and around 155 species had been discovered.[3] 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.
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Amblypygids may be up to 30cm long. 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, and three smaller eyes placed further back on each side. The pedipalps are large and somewhat pincer-like, being adapted for grabbing prey.[5]
As in some other arachnid orders, the first pair of legs are modified to 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 have no silk glands or venomous fangs.
Amblypygids often move about sideways on their six walking legs, with one "whip" pointed in the direction of travel while the other probes their other sides. Prey are located with these "whips", captured with pedipalps, then masticated with chelicerae.
Courting rituals involve the male depositing stalked spermatophores, which have one or more sperm masses at the tip, onto the ground, and using his pedipalps to guide the female over them.[6] She gathers the sperm and lays fertilized eggs into a sac carried under the abdomen. When the young hatch, they climb up onto the mother's back; any which fall off before their first moult will be eaten by the mother.
Amblypygids, particularly the species Phrynus marginemaculatus and Damon diadema, are thought to be among the few examples of arachnids which show signs of social behavior. Research conducted by entomologists at Cornell University suggests that mother amblypygids communicate with their young by caressing the offspring with her anteniform front legs, and that the offspring reciprocate both with their mother and their siblings. Further, in an experiment where two or more siblings were placed in an unfamiliar environment, such as a different cage, they would seek each other out and gather back into a group.[7]
Fossilized amblypygids have been found dating back to the Carboniferous period, for example Graeophonus.
The following genera are recognised:[3]
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