page_title: Solifugae
section_title: Legs and pedipalps
hierarchical_section_title: Solifugae / Anatomy / Legs and pedipalps
caption_attribution_description: English: Modest-sized Solifugid near Uniondale, Western Cape, South Africa. The large fore-limbs are not legs, but pedipalps; note that they are held not quite touching the ground.
context_page_description: Solifugae is an order of animals in the class Arachnida known variously as camel spiders, wind scorpions, sun spiders, or solifuges. The order includes more than 1,000 described species in about 153 genera. Despite the common names, they are neither true scorpions nor true spiders. Much like a spider, the body of a solifugid has two tagmata: an opisthosoma, or abdomen, behind the prosoma, or cephalothorax. At the front end, the prosoma bears two chelicerae that, in most species, are conspicuously large. The chelicerae serve as jaws and in many species also are used for stridulation. Unlike scorpions, solifugids do not have a third tagma that forms a "tail". Most species of Solifugae live in dry climates and feed opportunistically on ground-dwelling arthropods and other small animals. The largest species grow to a length of 12–15 cm, including legs. A number of urban legends exaggerate the size and speed of the Solifugae, and their potential danger to humans, which is negligible.
context_section_description: Like most other arachnids, although Solifugae appear to have five pairs of legs, only the hind four pairs actually are "true" legs. Each true leg has seven segments: coxa, trochanter, femur, patella, tibia, metatarsus, and tarsus.
  The first, or anterior, 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 eversible adhesive organs, which they may use to capture flying prey, and which at least some species certainly use for climbing smooth surfaces.
  For the most part, only the posterior three pairs of legs are used for running. On the undersides of the coxae and trochanters of the last pair of legs, Solifugae have fan-shaped sensory organs called malleoli or racquet (or racket) organs. Sometimes, the blades of the malleoli are directed forward, sometimes not. They have been suspected to be sensory organs for the detection of vibrations in the soil, perhaps to detect threats and potential prey or mates. These structures may be chemoreceptors.
  Males are usually smaller than females, with relatively longer legs. Unlike females, the males bear a pair of flagella, one on each chelicera. In the accompanying photograph of a male solifugid, one flagellum is just visible near the tip of each chelicera. The flagella, which bend back over the chelicerae, are sometimes called horns and are believed to have some sexual connection, but their function has not yet been clearly explained.
caption: Male solifugid in South African veld: Its flagella are visible near the tips of the chelicerae, looking like large, backward-curling bristles. As in most species, it holds its pedipalps clear of the ground; its front legs serve as tactile sensors, barely touching the ground with their setae.
exif: {"Image Make": "Canon", "Image Model": "Canon PowerShot A650 IS", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2011:06:07 08:51:14", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "188", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "180", "Thumbnail YResolution": "180", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "3518", "Thumbnail JPEGInterchangeFormatLength": "8540", "EXIF ExposureTime": "1/800", "EXIF FNumber": "4", "EXIF ISOSpeedRatings": "80", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2010:10:17 16:24:40", "EXIF DateTimeDigitized": "2010:10:17 16:24:40", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "309/32", "EXIF ApertureValue": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "95/32", "EXIF MeteringMode": "CenterWeightedAverage", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "37/5", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3152", "EXIF ExifImageLength": "2244", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "Interoperability RelatedImageWidth": "4000", "Interoperability RelatedImageLength": "3000", "EXIF InteroperabilityOffset": "3370", "EXIF FocalPlaneXResolution": "4000000/291", "EXIF FocalPlaneYResolution": "1000000/73", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}