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Amblypygi

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Amblypygi is an order of arachnids commonly known as whip-spiders or tailless whip-scorpions. The name "amblypygid" translates to "blunt tail," which refers to the absence of a flagellum. This is a tail-like structure found in the related order Uropygi, often called vinegaroons. Unlike many other arachnids, amblypygids possess no venom glands and no silk glands.

Amblypygi-legs
Amblypygi-legs

While they rarely bite, they can grab fingers with their pedipalps, which may cause puncture injuries similar to thorns. As of 2023, scientists have identified approximately 260 species across 17 genera and five distinct families.

The anatomy of an amblypygid is highly specialized for a nocturnal lifestyle. Their bodies consist of two main segments: the prosoma, or cephalothorax, and the segmented opisthosoma, or abdomen. Most species possess eight eyes. These include a pair of median eyes at the front of the carapace and two smaller clusters of three eyes each located further back on the sides.

Phrynichus phipsoni – Pocock, 1900
Phrynichus phipsoni – Pocock, 1900

Their exoskeleton is protected by a super-hydrophobic coating. This water-repellent layer is formed by a colloidal secretion that self-assembles into hierarchical microstructures. Additionally, the exoskeleton is enriched with trace elements like calcium, magnesium, manganese, potassium, sodium, and zinc. These elements tend to accumulate as the individual grows older.

Amblypygids use their eight legs in a very specific way. They only use six legs for locomotion, often moving in a sideways, crab-like fashion. The first pair of legs is highly modified into thin, elongated sensory organs called antenniform legs. These legs act like antennae and can extend several times the length of the animal's body.

Amblypygi-legs
Amblypygi-legs

When these legs detect prey, the amblypygid uses its raptorial pedipalps to strike. These pedipalps are large, grasping appendages equipped with spines used to impale and immobilize victims. After the prey is caught, pincer-like chelicerae grind and chew the food before it is ingested.

Social behavior and reproduction are complex processes within this order. During courtship, a male deposits stalked spermatophores, which are sperm masses, onto the ground. He then uses his pedipalps to guide the female over these masses. After fertilization, the female carries the eggs in a sac under her opisthosoma.

Damon diadema female
Damon diadema female

When the young hatch, they climb onto the mother's back for protection. If they fall off before their first molt, they will not survive. Some species, such as Phrynus marginemaculatus and Damon diadema, exhibit rare social behaviors among arachnids. Research from Cornell University suggests that mothers communicate with their offspring using their antenniform legs.

The history of the Amblypygi extends deep into the geological past. Fossilized remains, such as the genus Weygoldtina, date back to the Carboniferous period. Other fossils, including Paracharonopsis, have been found in Eocene amber from India. There are also fossils from the Cretaceous period, such as those found in Burmese amber.

AmblypygiDorsal
AmblypygiDorsal

These findings show that the basic body plan of whip-spiders has been successful for hundreds of millions of years.

Amblypygids are found in tropical and subtropical regions throughout the world. They prefer warm, humid environments where they can remain hidden in leaf litter, caves, or under bark. Some species are even subterranean. Because they lack venom, they are often described as having a nervous temperament and will retreat when they sense a threat. They are opportunistic predators that primarily eat other arthropods, though they have been observed feeding on vertebrates. They may go for over a month without eating, which often occurs during the pre-molt stage.

Molting is a critical biological process for their growth. To molt, an amblypygid hangs from the underside of a horizontal surface. This allows the animal to use gravity to help separate the old exoskeleton from the new one.

Molting process of Tail-less Whip Scorpion from Sri Lanka
Molting process of Tail-less Whip Scorpion from Sri Lanka

Because of their unique appearance, several genera are popular in the pet trade. Genera such as Acanthophrynus, Charinus, and Phrynus are commonly kept in tall enclosures. These enclosures must provide vertical space for climbing and molting, as well as high humidity, typically above 75%. In captivity, these animals can live between 5 and 10 years.

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🖼️ Images & Media (6)
File:AmblypygiDorsal.jpg
AmblypygiDorsal.jpg
File:Phrynichus phipsoni – Pocock, 1900.png
Phrynichus phipsoni – Pocock, 1900.png
File:Damon diadema female.jpg
Damon diadema female.jpg
File:Amblypygi-legs.jpg
Amblypygi-legs.jpg
File:Molting process of Tail-less Whip Scorpion from Sri Lanka.jpg
Molting process of Tail-less Whip...
File:Damon johnstoni – Lydekker, 1879.png
Damon johnstoni – Lydekker, 1879.png
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