Temporal range: Upper Carboniferous–Recent
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 amblypygids possess very small, tail-like, terminal, opisthosmal segments and use a sort of "tail" to hang from while molting but actually lack a flagellum. The name "amblypygid" means "blunt rump", a reference to a lack of the flagellum ("tail") carried by the whip scorpions. 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 3 to 23.6 inches (7.6 to 60 cm) in size according to 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 that of crustaceans), and possessed three smaller eyes placed further back on each side, for a total of eight eyes.
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. 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.
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.
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. 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 not survive.
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.
Like many others of their species, Amblypygids like to be in tight, dark spaces. Amblypygids moisture needs are the most sensitive; if exposed to relatively short periods of dryness they will die.
Amblypygids will consume any sort of insect prey. The size of the insect depending very much on the size of the creature. Like most arachnids, amblypygids only need to feed once a week, and can go for two or three weeks without food. If the animal is molting, ready to molt, or has just molted, they generally do not feed
Like any other arachnid, an amblypygid will molt several times during its life.
During the courtship period, the male and female will be in close contact. After courtship is ended, the pair will become uninterested in one another. If the male and female are no longer in close contact, and are resting apart, then the courtship period has come to a close. The female can become very aggressive while carrying her brood sac and protecting her young. Aside from this and their extreme sensitivity to vibrations and disturbances, amblypygids are fairly easy to breed and are sometime kept as exotic pets despite, or possibly due to, their unusual appearance even when compared to other arachnids .
The following genera are recognised:
- Charinidae Weygoldt, 1996
- Charontidae Simon, 1892
- Phrynichidae Simon, 1900
- Damon C. L. Koch, 1850 (10 species)
- Musicodamon Fage, 1939 (1 species)
- Phrynichodamon Weygoldt, 1996 (1 species)
- Euphrynichus Weygoldt, 1995 (2 species)
- Phrynichus Karsch, 1879 (16 species)
- Trichodamon Mello-Leitão, 1935 (2 species)
- Xerophrynus Weygoldt, 1996 (1 species)
- Phrynidae Blanchard, 1852
- Heterophrynus Pocock, 1894 (14 species)
- Acanthophrynus Kraepelin, 1899 (1 species)
- †Electrophrynus Patrunkevich, 1971 (1 species; Late Oligocene – Early Miocene)
- Paraphrynus Moreno, 1940 (18 species)
- Phrynus Lamarck, 1801 (28 species, Oligocene - Recent)
- Paracharontidae Weygoldt, 1996
- † Sorellophrynus Harvey, 2002 (1 species, Upper Carboniferous)
- † Thelyphrynus Petrunkevich, 1913 (1 species, Upper Carboniferous)
- "Pedipalpi". The international wildlife encyclopedia 1 (3 ed.). Tarrytown, NY: Marshall Cavendish. 2002. p. 1906. ISBN 0-7614-7267-3. Retrieved 2011-10-29.
- Takashima, Haruo (1950). "Notes on Amblypygi Found in Territories Adjacent to Japan". Pacific Science 4 (4): 336–338. ISSN 0030-8870. hdl:10125/9019.
- Mark S. Harvey (2003). "Order Amblypygi". Catalogue of the smaller arachnid orders of the world: Amblypygi, Uropygi, Schizomida, Palpigradi, Ricinulei and Solifugae. CSIRO Publishing. pp. 3–58. ISBN 978-0-643-06805-6.
- R. I. Pocok (1900). Fauna of British India. Arachnida.
- Robert D. Barnes (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 617–619. ISBN 0-03-056747-5.
- Peter Weygoldt (1999). "Spermatophores and the evolution of female genitalia in whip spiders (Chelicerata, Amblypygi)" (PDF). Journal of Arachnology 27 (1): 103–116.
- Jeanna Bryner (March 19, 2007). "Creepy: Spiders Love to Snuggle". LiveScience. Archived from the original on July 25, 2008.
- Dunlop, J.A.; Zhou, G.R.S.; Braddy, S.J. (2007). "The affinities of the Carboniferous whip spider Graeophonus anglicus Pocock, 1911 (Arachnida:Amblypygi)". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 98: 165–178. doi:10.1017/S1755691007006159.
|Wikimedia Commons has media related to Amblypygi.|
- Data related to Amblypygi at Wikispecies
- Picture of a Mexican amblypygid (referred to as a "tailless whip scorpion") and its habitat
- Amblypigid video summarizing research from University of Nebraska's Eben Gering.
- NPR Science Friday show that makes mention
- Amblypygi. The Antillean (West Indian) fauna.