Roller spider ( Solifugae spec. )
|Sundevall , 1833|
The roller spiders (Solifugae, also Solpugida) form an order of the arachnids (Arachnida), which includes over 900 species. Contrary to what the name might suggest, the non-toxic roller spiders are not "real" spiders .
The largest roller spiders can measure up to 70 mm from head to abdomen, but most species are much smaller. Characteristic is the clearly articulated, elongated abdomen , usually in its entire width attached to the articulated foreleg , consisting of eleven segments. Further characteristics are the very large, scissor-shaped jaw claws ( chelicerae ) with blistering at the base and the leg-shaped jaw button pairs ( pedipalps ) that work vertically against each other . Roller spiders have legs ending in two long foot claws, which are covered with long, brittle hair. The body can be covered with thick felt.
As sensory organs, the roller spiders have a pair of large individual eyes directly above the chelicera base and one or two pairs of reduced side eyes. In addition, there are long tactile bristles and adhesive organs on the pedipalps, which are designed as large tactile legs, as well as five hammer-shaped organs (malleoli) on the last pair of legs, which probably serve as chemoreceptors . The first pair of legs is also used as a feeler leg, so that the roller spiders only run on six legs.
Way of life of the roller spiders
The roller spiders mostly live in arid areas, especially in deserts and steppes . Some species can be found in the Mediterranean area. Most species are active at night or at dusk and spend most of the day in self-dug tubes under stones. The North American species Mossamedessa abnormalis lives largely underground. There are also species that are diurnal and look for prey in the sun when the temperature is high. In general, little is known about the way of life of many types of roller spiders; only a few have been examined more closely.
Roller spiders feed in particular on insects , spiders , scorpions , other roller spiders and even small reptiles . They are actively looking for prey that is held in place by the pedipalps and actively chopped up by the heavy chelicerae. The food is pre-digested outside the body and then enters the digestive tract in a pulpy form. These animals lack poison glands. In case of danger, the roller spiders threaten the potential attacker with the chelicerae, whereby some species can also stridulate by rubbing the pincers together . In relation to body size, the chelicerae are among the most powerful biting tools in the animal kingdom. They can work on rock and tear deep flesh wounds in tough carcasses and on mammals. Their bite is very painful to humans and can cause large swelling from infection.
Roller spiders are extremely fast in their locomotion, which they often interrupt jerkily, which is probably due to the fact that the animals only have trachea as respiratory organs . Roller spiders are aggressive animals that often confront larger opponents, but usually only attack them when they feel threatened. Therefore, bite wounds in humans are rather rare and mostly due to mistakes in handling these animals.
During the very short and violent courtship of the roller spiders, the male grabs the female with the chelicerae, throws it on its back and works the genital region with a specially designed bristle on the chelicerae, which is called the flagellum. Then a sperm packet ( spermatophore ) of the male is transferred either with the chelicerae (in Othoes saharae ) or directly from the male genital opening (in Eremobates durangonus ) into the female genital opening.
The male must be careful when withdrawing, as otherwise it can be viewed and eaten by the female as prey ( cannibalism ). If the female is already pregnant or does not want to mate for other reasons, the male is also regarded as prey and eaten.
The eggs are laid in specially dug brood chambers. The eggs are guarded and defended here by the females ( brood care ). Over several nymph stages (number different according to species) the animals develop into full-grown roller spiders.
Roller spiders and people
Their appearance and the speed with which many roller spiders move have led to a variety of names and designations (e.g. wind scorpions, sun spiders, camel spiders, hair-cutters ) and to exaggerations and legends. In fact, the non-poisonous animals are not dangerous to humans, although larger specimens can cause painful wounds in the skin with their chillies.
Because of their speed and ferocity, roller spiders were unleashed on other roller spiders or scorpions for entertainment purposes, for example by British soldiers stationed in Libya.
The closest relatives of the roller spiders are the pseudoscorpions , with whom they share the similar chelicere (which, however, is much smaller in the pseudoscorpions) and the structure of their tracheal system.
A distinction is made between the following 12 families within the roller spiders:
- Ammotrechidae Roewer , 1934
- Ceromidae Roewer , 1933
- Daesiidae Kraepelin , 1899
- Eremobatidae Kraepelin , 1901
Galeodidae Sundevall , 1833
- Camel spider ( Galeodes arabs C. L. Koch , 1842 )
- Gylippidae Roewer , 1933
- Hexisopodidae Pocock , 1897
- Karschiidae Kraepelin , 1899
- Melanoblossidae Roewer , 1933
- Mummuciidae Roewer , 1934
- Rhagodidae Pocock , 1897
- Solpugidae Leach , 1815
Fossil roller spiders are extremely rare. In total, only four finds are known. The oldest fossil was found in the Pennsylvania ( Upper Carboniferous ) of Mazon Creek (USA) . One specimen comes from the Tertiary ( Eocene to Miocene ) Dominican amber and two more from the Eocene / Oligocene Baltic amber .
- Fred Punzo: The biology of camel-spiders: Arachnida, Solifugae . Springer Science & Business Media, New York 1998, 301 pp.
- Peter Weygoldt: Solifugae (Solpugida), roller spinning. In: Westheide, Rieger (Ed.): Special Zoology Part 1: Protozoa and invertebrates. Gustav Fischer Verlag, Stuttgart, Jena 1997, pp. 484-485
- International Society for Arachnology solifuge links
- Roller spinning in Europe (PDF file; 58 kB)
- Global Survey and Inventory of Solifugae - Homepage of the Arachnid Order Solifugae . in engl. Retrieved March 8, 2011.
- Camel Spider Feeding by Stefan F. Wirth
- Fred Punzo: The Biology of Camel-Spiders: Arachnida, Solifugae . Springer Science & Business Media, New York 1998, ISBN 978-0-7923-8155-6 , pp. 301 .
- Berg, R., J. Berg & P. Berg (2018): Namibia for arthropod fans: On the trail of the "Little five hundred". - Draco 16: 60-67.
- George O. Poinar, Jr .: Life in Amber . 350 pp., 147 figs., 10 plates, Stanford University Press, Stanford (Cal.) 1992, ISBN 0-8047-2001-0 .
- AH Müller: Textbook of Palaeozoology, Volume II, Invertebrates, Part 2, Mollusca 2 - Arthropoda 1 , Jena 1991.
- C. Gröhn: Inclusions in Baltic amber. Kiel / Hamburg 2015, ISBN 978-3-529-05457-0 .