Of all the animals that you may encounter in a tropical rainforest, none evoke a more visceral, negative reaction in even the most ardent nature lovers than the tailless whipscorpions...
The Amblypygi are a group of around 150 species of arachnids commonly known as tailless whip scorpions or whip spiders (Harvey 2002, 2003). In contrast to the Uropygi [=Thelyphonida] (whip scorpions or vinegaroons), amblypygids lack a tail. The long, bulky, and spined pedipalps extending in front of their somewhat flattened bodies are raptorial (i.e., adapted for seizing prey) and the first pair of walking legs are highly modified into very long antenna-like sensory appendages. Amblypygids lack the silk-spinning spinnerets or poison glands of spiders, but their chelicerae are modified as spider-like fangs. (Barnes 1987; Brusca and Brusca 2003) Either the Uropygi or Araneae (spiders) are believed to be the sister clade to the Amblypygi, with Uropygi generally viewed as more likely given current knowledge (Weygoldt 2000; Fahrein et al. 2009).
Amblypygids are widely distributed in warm, humid regions, where they are typically found in protected situations such as under bark or in leaf litter. Some live in caves. Most species are less than 5 cm long (the smallest is less than a centimeter), but the antenniform first pair of legs may be as long as 25 cm. These long "legs" function as both touch receptors and chemoreceptors. Amblypygids hunt at night, walking sideways with their front "legs" extended. When a prey item is encountered, it is grabbed with the pedipalps and torn open with the chelicerae, allowing the body fluids to be imbibed. (Barnes 1987; Brusca and Brusca 2003)
In the few amblypygid species in which reproductive behavior has been observed, the male courts the female with trembling movements of the antenniform legs and rocking body movements directed toward the female. Eventually, a sperm-containing spermatophore is deposited. Using his pedipalps or front legs, the male guides the female over the spermatophore, which she takes up. After fertilization occurs, the female produces a parchment-like membrane that holds her 6 to 60 large eggs underneath her abdomen. She carries the eggs until hatching and subsequently carries the newly hatched offspring. After their first molt, the young amblypygids climb onto the mother's abdomen until the next molt. (Barnes 1987; Brusca and Brusca 2003)
Amblypygids typically feed on arthropods such as crickets, katydids, harvestmen, spiders, millipedes, roaches, and moths (which they are able to snatch out of the air!) (Hebets 2002), but Ladle and Velander (2003) reported a very unusual feeding habit for a Caribbean species inhabiting rocky outcrops adjacent to mountain streams running through primary tropical rainforest on the island of Tobago: here, Heterophrynus cheiracanthus were observed capturing and eating Macrobrachium prawns plucked from the stream.
Rayor and Taylor (2006) reported on their observations of social behavior in amblypygids, which are generally viewed as solitary animals, and review the literature on early parental care and more complex social behaviors in non-spider arachnids in general.
Weygoldt et al. (2010) described the mating and reproductive behavior of Phrynus exsul, the only Old World species of the family Phrynidae (an essentially Neotropical group), and compare it to that of other phrynids. The Neotropical Phrynus were revised by Quintero (1981).
Harvey (2003) provides a dichotomous key to families and a world catalogue of species. Weygoldt (2000) reviewed the biology of the Amblypygi and includes a key to genera as well as basic information about each genus (distinguishing characteristics, geographic distribution, key literature, etc.).
Amblypygi is an order of arachnid chelicerate arthropods also known as whip spiders or tailless whip scorpions (not to be confused with whip scorpions or vinegaroons that belong to the related order Thelyphonida). The name "amblypygid" means "blunt tail", a reference to a lack of the flagellum that is otherwise seen in whip scorpions. Amblypygids possess no silk glands or venomous fangs. They rarely bite if threatened, but can grab fingers with their pedipalps, resulting in thorn-like puncture injuries.
As of 2016, 5 families, 17 genera and around 155 species had been discovered and described.[2] They are found in tropical and subtropical regions worldwide; they are mainly found in warm and humid environments and like to stay protected and hidden within leaf litter, caves, or underneath bark. Some species are subterranean; all are nocturnal. Fossilized amblypygids have been found dating back to the Carboniferous period, such as Weygoldtina.[1]
Amblypygids range from 5 to 16 centimetres (2.0 to 6.3 in) in legspan.[2][4] Their bodies are broad and highly flattened, with a solid carapace and a segmented abdomen, or opisthosoma. Most species have eight eyes; a pair of median eyes at the front of the carapace above the chelicerae and 2 smaller clusters of three eyes each further back on each side.
Amblypygids have raptorial pedipalps modified for grabbing and retaining prey, much like those of a mantis;[5] recent work suggests that the pedipalps display sexual dimorphism in their size and shape.[6] 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 the body.[2]
Amblypygids have eight legs, but use only six for walking, often in a crab-like, sideways fashion. The front pair of legs are modified for use as antennae-like feelers, with many fine segments giving the appearance of a "whip". When a suitable prey is located with the antenniform legs, the amblypygid seizes its victim with large spines on the grasping pedipalps, impaling and immobilizing the prey. This is typically done while climbing the side of a vertical surface and looking downward at their prey.[7] Pincer-like chelicerae then work to grind and chew the prey prior to ingestion. The tailless whip scorpion may go for over a month in which no food is eaten; often this is due to premolt. Due to the lack of venom the tailless whip scorpion is very nervous in temperament, retreating away if any dangerous threat is sensed by the animal.
Courtship involves 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.[8] She gathers the sperm and lays fertilized eggs into a sac carried under the abdomen, or opisthosoma. When the young hatch, they climb up onto the mother's back; any which fall off before their first molt will not survive.
Some species of amblypygids, 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 antenniform front legs, and the offspring reciprocate both with their mother and siblings. The ultimate function of this social behavior remains unknown.[9] Amblypygids hold territories that they defend from other individuals.[10]
The amblypygid diet mostly consists of arthropod prey, but these opportunistic predators have also been observed feeding on vertebrates.[2] Amblypygids generally do not feed before, during, and after molting. Like other arachnids, an amblypygid will molt several times during its life.[2] Molting is done from hanging from the underside of a horizontal surface in order to use gravity to assist in separating the old exoskeleton from the animal.
Several species of Amblypygi are sold and kept as pets including Damon diadema, Damon medius, Damon variegatus, Euphrynichus amanica, Heterophrynus batesii, Acanthophrynus coronatus, Phrynus marginemaculatus and Paraphrynus mexicanus.[11] Tailless whip scorpions are kept in tall (>45 cm;>18 in) glass enclosures which allow for two things: Enough vertical space for climbing and moulting, and enough space for heat to dissipate in order to keep the enclosure between 70 °F (21 °C) and 75 °F (24 °C). 5 centimetres (2.0 in) of substrate at the bottom of the enclosure is generally sufficient to allow for burrowing and also serves as a method to retain water in order to keep the humidity above 75%. Tailless whip scorpions live anywhere between 5–10 years. Feeding can include small insects such as crickets, mealworms, and roaches.[12][13]
The following genera are recognised:[14][15]
Amblypygi is an order of arachnid chelicerate arthropods also known as whip spiders or tailless whip scorpions (not to be confused with whip scorpions or vinegaroons that belong to the related order Thelyphonida). The name "amblypygid" means "blunt tail", a reference to a lack of the flagellum that is otherwise seen in whip scorpions. Amblypygids possess no silk glands or venomous fangs. They rarely bite if threatened, but can grab fingers with their pedipalps, resulting in thorn-like puncture injuries.
As of 2016, 5 families, 17 genera and around 155 species had been discovered and described. They are found in tropical and subtropical regions worldwide; they are mainly found in warm and humid environments and like to stay protected and hidden within leaf litter, caves, or underneath bark. Some species are subterranean; all are nocturnal. Fossilized amblypygids have been found dating back to the Carboniferous period, such as Weygoldtina.
