Solifugae - WikiHQ

Solifugae is an order of arachnids known variously as jerrymanders, These animals have a number of common names, including sun spiders, wind scorpions, wind spiders, red romans, and camel spiders. In practice, the respective lengths of the legs of various species differ greatly, so the resulting figures are often misleading. More practical measurements refer primarily to the body length, quoting leg lengths separately, if at all. The body length is up to . Most species are closer to long, and some small species are under in head-plus-body length when mature. The abdominal tergites and sternites are separated by large areas of intersegmental membranes, giving it a high degree of flexibility and ability to stretch considerably, which allows it to consume a large amount of food. The chelicerae serve as jaws, and in many species also are used for stridulation. Unlike scorpions, solifuges do not have a third tagma that forms a "tail".

thumb|left|300x300px|Solifuge eyes with bristly [[setae]]

Solifuges have a pair of large central eyes known as median ocelli. The eyes have a pigment-cup structure and are covered by a domed outer lens made from the animal's exoskeleton.

In addition to the median eyes, solifuges possess a pair of vestigial lateral ocelli. These eyes are found in pits on the animal's cephalic lobes near the chelicerae. These ocelli's lenses are usually atrophied. However, in some species both nerves and pigment cells are present. In species where lateral eyes are functional, they probably aid in detecting motion or changes in brightness. Air sacs are attached to the branching tracheae, with tracheoles penetrating the epithelia of internal organs. Hemocyanin, a respiratory pigment common in the hemolymph of many arachnids and other arthropods, is absent. As embryos they also have opisthosomal protuberances resembling the pulmonary sacs found in some palpigrades. They utilize discontinuous gas exchange almost identical to that of insects, where they go through periods where the spiracles are closed, followed by a phase with open spiracles to allow gas exchange.

Solifuges are somewhat sexually dimorphic, with the smaller males often possessing longer legs. forming a powerful pincer, much like that of a crab; each article bears a variable number of teeth, largely depending on the species. Many Solifugae stridulate with their chelicerae, producing a rattling noise.

thumb|Ventral aspect of a solifuge, showing spiracles and malleoli

The first or anterior pair of the five pairs of leg-like appendages are not "actual" legs, but pedipalps, and they have only five segments each. The pedipalps of the Solifugae function partly as sense organs similar to insects' antennae, and partly in locomotion, feeding, and fighting. In normal locomotion, they do not quite touch the ground, but are held out to detect obstacles and prey; in that attitude, they look particularly like an extra pair of legs or perhaps arms. Reflecting the great dependence of the Solifugae on their tactile senses, their anterior true legs commonly are smaller and thinner than the posterior three pairs. That smaller anterior pair acts largely in a sensory role as a supplement to the pedipalps, and in many species they accordingly lack tarsi. At the tips of their pedipalps, Solifugae bear a membranous suctorial organ, which are used for capturing prey, and also for bringing water to their mouthparts for drinking and climbing smooth surfaces. For the most part, only the posterior three pairs of legs are used for running. being the analogues of pectines in scorpions, and modified walking limbs in the uropygids and amblypygids as well as the pedipalps in spiders and other arachnids. Generally, solifuges have five pairs of malleoli on the ventral surface of the fourth pair of legs. Malleoli are usually larger in males. A malleolus comprises a basal stalk and a triangular fan, with epicuticular protrusions on each anterior face, and granular structures on each stalk, with undulated surfaces at each distal end. Sometimes, the blades of the malleoli are directed forward, sometimes not.

Spermatogenesis occurs prior to adulthood. When reaching the adult stage, the testicles have already degenerated, and adult males store a finite supply of sperm. In some, like the Galeodidae, the male deposits sperm on the substrate and transfers it into the female using his chelicerae, whereas other males show more direct transfer, such as the Metasolpuga, which deposit sperm on the females' body dorsum, and the Eremobatidae, which place a spermatophore directly on the females' genitals through gonopore-to-gonopore contact, before pushing it into her body with his chelicerae. During mating with female inactivity, the male grasps and manipulates the female, turning her onto her back, and uses his chelicerae in chewing movements within the genital opening both before and after sperm transfer.

The female then digs a burrow, into which she lays 50 to 200 eggs; some species then guard them until they hatch. Because the female does not feed during this time, she tries to fatten herself beforehand, and a species of has been observed to eat more than 100 flies during that time in the laboratory. torpor, or hibernation) in times such as during "unseasonable conditions" unsuitable for them (such as high rainfall or cold temperatures).

Classification and phylogeny

Solifuges are an order of arachnids comprising over 1200 species in at least 146 genera assigned to 16 different families. They can be divided into two groups of families, which are recognized as distinct suborders. When looking at their relationships, the families Ammotrechidae and Daesiidae were found to be paraphyletic, leading to multiple clades without a name. Anton August Heinrich Lichtenstein theorized in 1797 that the "mice" that plagued the Philistines in the Old Testament were Solifugae. During World War I, troops stationed in Abū Qīr, Egypt, would stage fights between captive "jerrymanders", as they referred to them, and placed bets on the outcome. Similarly, British troops stationed in Libya in World War II staged fights between solifuges and scorpions. One 1978 study is frequently quoted, in which the authors report detection of an exception in India, in that Rhagodes nigrocinctus had venom glands, and that injection of the secretion into mice was frequently fatal, but no supporting studies have confirmed either statement, such as by independent detection of the glands as claimed, or the relevance of the observations, if correct. Even the authors of the original account admitted to having found no means of delivery of the putative venom by the animal, and the only means of administering the material to the mice was by parenteral injection. Given that many nonvenoms such as saliva, blood, and glandular secretions can be lethal if injected, and that no venomous function was even speculated upon in this study, evidence for even one venomous species of solifuge is yet to be found. An Arizona resident developed painful lesions due to a claimed solifuge-bite but could not produce a specimen for confirmation. Though they are not venomous, the powerful chelicerae of a large specimen may inflict a painful nip, but nothing medically significant.

Claims that the Solifugae aggressively chase people are also untrue, as they are merely trying to stay in the shade/shadow provided by the human.

Notes

References

External links

Camel Spider Feeding by Stefan F. Wirth

Classification and phylogeny

Notes

References

Further reading

External links