Amblypygi

Amblypygi Temporal range: Upper Carboniferous–Recent PreЄ Є O S D C P T J K Pg N
File:Heterophrynus 02.jpg
Heterophrynus, Ecuador
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Arachnida
Order:	Amblypygi Thorell, 1883
Families
Paracharontidae Charinidae Charontidae Phrynichidae Phrynidae

Amblypygi is an order of arachnid chelicerate arthropods.

Amblypygids are also known as whip spiders and tailless whip scorpions (not to be confused with whip scorpions and vinegaroons that belong to the related order Thelyphonida). The name "amblypygid" means "blunt rump", a reference to a lack of the flagellum ("tail") that is otherwise seen in whip scorpions. They are harmless to humans. Amblypygids possess no silk glands or venomous fangs. They rarely bite if threatened, but can grab fingers with pedipalps, resulting in thorn-like puncture injury.

By 2003, 5 families, 17 genera and around 155 species had been discovered and described. They are found in tropical and subtropical regions worldwide. Some species are subterranean; all are nocturnal. Fossilized amblypygids have been found dating back to the Carboniferous period, such as Graeophonus.

Physical description

File:AmblypygiDorsal.jpg

Detail of pedipalps

Parts of an amblypygid, from Pocock (1900)

Amblypygids range from 5 to 60 centimetres (2.0 to 23.6 in) 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 eye pairs placed further back on each side, for a total of eight eyes.

Amblypygids possess medium to poor eyesight. Their pedipalps, which serve as sensors for many related arachnids, are modified for grabbing and retaining prey, much like those of a mantis. The first pair of legs act as sensory organs and are not used for walking. The sensory legs are very thin and elongate, 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.

Behavior

File:Damon diadema female.jpg

Damon diadema mother carrying young

Amblypygids often move about sideways on their six walking legs, but as arachnids have eight legs. The front pair are highly modified with many fine segments giving the appearance of a "whip". One of the "whips" is typically pointed in the direction of travel, while the other probes their other sides. Prey are located with these "whips" often circled around touching it from behind, then captured with the long spines on the grasping pedipalps, before being masticated with central pincer-like chelicerae.

File:Amblypygi-legs.jpg

Comparing the front and back legs of an Amblypygid

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.

Some species of Amblypygi, particularly Phrynus marginemaculatus and Damon diadema, may be among the few examples of arachnids that exhibit social behavior. Research conducted at Cornell University suggests that mother amblypygids communicate with their young with her anteniform front leg, and the offspring reciprocate both with their mother and siblings. Further, the whip spiders would seek each other out and gather into a group when placed in an unfamiliar environment.

Amblypygids will consume any appropriately sized prey. Most of their diet likely consists of insects. Like many opportunistic predators, amblypygids can survive for two or three weeks without food. Before, during and after molting they generally do not feed. Like any other arachnid, an amblypygid will molt several times during its life.

General

File:AmblypgiLyd.png

Damon johnstonii from West Africa

The following genera are recognised:

Palaeoamblypygi Weygoldt, 1996

Paracharontidae Weygoldt, 1996

• †Graeophonus Scudder, 1890 (2-3 species, Carboniferous)
• Paracharon Hansen, 1921 (1 species)
• †Paracharonopsis Engel & Grimaldi, 2014 (1 species, Eocene)

Euamblpygi Weygoldt, 1996

Charinidae Weygoldt, 1996

• Catageus Thorell, 1889 (1 species)
• Charinus Simon, 1892 (33 species)
• Sarax Simon, 1892 (10 species)

Neoamblpygi Weygoldt, 1996

Charontidae Simon, 1892

• Charon Karsch, 1879 (5 species)
• Stygophrynus Kraepelin, 1895 (7 species)

Unidistitarsata Engel & Grimaldi, 2014

family unspecified

• †Kronocharon Engel & Grimaldi, 2014 (1 species, Cretaceous)

Phrynoidea Blanchard, 1852

Phrynichidae Simon, 1900

• Damon C. L. Koch, 1850 (10 species)
• Euphrynichus Weygoldt, 1995 (2 species)
• Musicodamon Fage, 1939 (1 species)
• Phrynichodamon Weygoldt, 1996 (1 species)
• Phrynichus Karsch, 1879 (16 species)
• Trichodamon Mello-Leitão, 1935 (2 species)
• Xerophrynus Weygoldt, 1996 (1 species)

Phrynidae Blanchard, 1852

• Acanthophrynus Kraepelin, 1899 (1 species)
• †Britopygus Dunlop & Martill, 2002 (1 species; Cretaceous)
• †Electrophrynus Petrunkevich, 1971 (1 species; Miocene)
• Heterophrynus Pocock, 1894 (14 species)
• Paraphrynus Moreno, 1940 (18 species)
• Phrynus Lamarck, 1801 (28 species, Oligocene - Recent)

incertae sedis

• † Sorellophrynus Harvey, 2002 (1 species, Upper Carboniferous)
• † Thelyphrynus Petrunkevich, 1913 (1 species, Upper Carboniferous)

In popular culture

A CGI representation of a whip spider appears in the film Harry Potter and the Goblet of Fire as the creature Mad-eye Moody demonstrates the three Unforgivable Curses on.

External links

• Data related to Amblypygi at Wikispecies
• Amblypigid video summarizing research from University of Nebraska's Eben Gering
• Amblypygi. The Antillean (West Indian) fauna.