Solifugae (solifuges, solifugids, solpugids)

sun spiders, red romans, wind scorpions, wind spiders, camel spiders, jerrymanders [English alternative names]; haarskeerders, baardskeerders, rooimanne, jag spinnekoppe ('hunting spiders'), gift-kankers ('poison cancers'), vetvreters ('fat eaters') [Afrikaans]

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthropoda > Arachnomorpha > Cheliceriformes > Chelicerata > Euchelicerata > Arachnida

Solifuge [image N. Larsen ©]

Images of unidentified species...

Families native to southern Africa

There are 12 families, 140 genera and 1075 species of solifuges worldwide, with six families, 30 genera and 241 species recorded from southern Africa. Thus, 22% of the world solifuge species occur in southern Africa. The Northern Cape (81 species) and Namibia have the highest number of species. The Orange River does not restrict their distribution. Information from Dippenaar-Schoeman et al. (2006) and Harvey (2003).

Ceromidae An African family of solifuges, containing three genera and 20 species. All three genera, and 11 species have been recorded from southern Africa.
Daesiidae Occurs in Africa, southern Europe and the Middle East, and further east to Central Asia and China. There are also a few species in the southern parts of South America. There are 28 genera and 189 species worldwide, with six genera and 89 species native to southern Africa.
Gylippidae Distribution includes Africa, the Middle East and Asia (including China). There are five genera and 26 species, of which three genera and seven species occur in southern Africa.
Hexisopodidae A near endemic family to southern Africa, recorded as far north as Angola and Zambia. There are two genera and 23 species, with both genera and 21 species recorded from southern Africa.
Melanoblossidae Endemic to southern Africa, except for one genus and species in its own subfamily that occurs in South-East Asia. There are six genera and 16 species of which five genera and 15 species occur in southern Africa.
Solpugidae A predominantly African family of solifuges but its distribution also includes southern Europe, the Middle East and Central Asia. There are 17 genera and 191 species, with 11 genera and 98 species native to southern Africa.

Introduction

This group of arachnids has various common names most of which suggest that they are spiders, which they are not. The only obvious similarity they share with spiders is the fact that they have eight legs. Solifuges are solitary, have no venom glands and are not a threat to people although they are very aggressive and fast moving and can inflict a painful bite.

The name of the solifuge originates from the Latin ‘solifuga’ (a kind of venomous ant, or spider) that is in turn derived from ‘fugere’ (to flee; fly, run away) and ‘sol’ (sun). There are a number of common names in both English and Afrikaans for these distinctive creatures, many of which include the term 'spider' or even 'scorpion'. Although it is neither of these, "spider" is preferred to "scorpion". The term 'sun spider' applies to those species active during the day that tend to avoid the heat and dash from shadow to shadow - often of a person - giving the alarming impression that they are giving chase. The term 'red roman' probably originates from the Afrikaans term 'rooiman' (red man) due to the red-brown colour of some species. The popular terms 'haarskeerders' and 'baardskeerders' (Afrikaans for hair and beard cutters) originate from the strange behaviour of some of these animals where they use hair shed from animals. It appears that female solifuges find hair to be an ideal nest liner. Reports from Gauteng suggested that Solifuges cut hair off the scalps of people without them being aware of it. Solifuge chelicerae are not adapted for cutting hair and until this can be proven it must remain a myth, although they are able to crush the shaft of bird feathers. Other names include jagspinnekoppe, vetvreters, sun spiders, jerrymanders, jerrymunglums, roman spiders, wind scorpions, wind spiders or camel spiders. They are believed, by some researchers, to be closely related to the Pseudoscorpiones but this is refuted by the latest research. There is a hamlet in the Western Cape called Baardskeersdersbos in honour of this fascinating arachnid.

Solifuges fluoresce under specific UV light of the correct wavelength and wattage and although they do not fluoresce as brightly as scorpions this is a method of collecting them. LED UV torches do not presently work on solifuges. Little is known about this fascinating order. Research is needed as well as a specific book to help understand and identify these fearsome but completely harmless creatures.

Morphology


Solifuge male head with flagellum. [image N. Larsen ©]	Solifuge male head seen ventrally. [image N. Larsen ©]

Solifuge palp with suctorial organ. [image N. Larsen ©]	Solifuge segmented tarsus and claws. [image N. Larsen ©]

Underside of solifuge showing malleoli on the fourth pair of legs. [image N. Larsen ©]

The solifuges body is divided in two parts: a prosoma (carapace) and the opisthosoma (abdomen).

The prosoma is divided into three sections:

the propeltidium (head) contains the chelicerae, eyes, pedipalps and first two pairs of legs.
the mesopeltidium contains the third pair of legs.
the metapelptidium contains the forth pair of legs.

Solifuges appear to have 10 legs but in fact, the first pair of appendages is the pedipalps that are very strong and are used for various functions such as drinking, catching, feeding, mating and climbing.

The most unusual feature is the unique suctorial organs on the tips of their pedipalps. Some solifuges are known to be able to use these organs to climb vertical surfaces, but this does not appear to be required in the wild. All the legs have a sub divided femur (prefemur and postfemur) while the tarsus may, or may not, be segmented with tarsal claws, The first pair of legs is thin and short and used as tactile organs (feelers) and not for locomotion and may or may not have tarsal claws. Solifuges, together with pseudoscorpions, lack a patella (a leg segment found in spiders, scorpions, and other arachnids). The fourth pair of legs is the longest and carries the malleoli, unique racquet organs, on the coxa and subdivided trochanter and probably have chemosensory properties. Most species have 5 pairs of malleoli while juveniles and some species only have 2-3 pairs.

Solifuges vary in size (10-70mm body length) and can have a leg span up to 160 mm. The head is large, supporting large strong chelicerae (jaws). The propeltidium (carapace) is raised to house the enlarged muscles that control the chelicerae. Because of this raised structure the name “camel spiders” is used in America. The chelicera has a dorsal fixed finger and a movable ventral finger, both armed with cheliceral teeth for crushing prey. These teeth are one of the features used in identification. The rostrum (mouth) is situated between the pedipalpal coxa. Solifuges have two simple eyes on a raised ocular tubercle on the anterior edge of the propeltidium but it is not yet known if it is only to detect light or darkness or has a visual capability. There is a belief that the vision may be acute and even used to watch for aerial predators. It is stated that the eyes are very complex so further research is needed. Rudimentary lateral eyes are usually absent.

The opisthosoma (abdomen) consists of eleven somites (segments) and it is considered that the metapeltidium is regarded as the first of the segments or alternatively covers the first. The somites are covered dorsally by a tergite and ventrally by a sternite. The abdomen is soft and expandable that enables the animal to eat large amounts of food. Solifuges, similar to pseudoscorpions and harvestmen, lack book lungs, replaced ventrally by two tracheal spiracles on the prosoma and two or three on the opisthosoma. The genitalia are situated on the 2nd sternite with the anal tubercle on the last somite.

Solifuges are mostly nocturnal but there are diurnal species that are usually more brightly coloured with light and dark bands running the length of the body, while the nocturnal species are a yellowish brown and often larger. The body of many species is covered with setae of various lengths, some up to 50mm resembling a shiny hair ball. Many of these setae are tactile sensors.

Food

Solifuges prey on various insects, spiders, scorpions, small reptiles, dead birds and even each other. Some species are exclusively termite predators. Some solifuges sit in the shade and ambush their prey. Others run their prey down and once they catch it they eat while the prey is still alive with vigorous ripping and cutting actions of the powerful jaws. Video footage has revealed that solifuges catch their prey with their forward stretched pedipalps using the distal suctorial organs to fasten onto the prey. The suctorial organ is usually not visible as it is encased in a dorsal and ventral cuticular lip. Once the prey has been caught and transferred to the chelicerae the sucktorial gland is enclosed. Haemolymph pressure is used to open and protrude the suctorial organ. This superficially resembles a shortened chameleon tongue. The adhesive properties appear to be van der Waals force.

Predators

Several raptors, owls and small mammals consume solifuges in their diets including the Bat-eared fox, Small-spotted genet, Cape fox, African civet and Black-backed jackal.

Reproduction

Male solifuges have aerial-like flagella on the chelicerae (like backward swept aerials), uniquely shaped for each species, that probably play some part in mating. Males may use these flagella to insert the spermatophore into the females’ genital opening. The male seeks out a female, using its suctorial organ he rips the female from her retreat, males use their pedipalps to coerce the female into a frozen state, and sometimes massages her abdomen with his chelicerae while he deposits a spermatophore in the female's genital opening. About 20 to 200 eggs are produced and hatch within about four weeks. The first stage of development, once hatched, is a larva and once the casing has cracked open the larva moults into a solifuge nymph. Solifuges live for about a year and pass through 9-10 instars before maturity. They are solitary animals living in scraped out sand retreats, often under rocks and logs or burrows up to 230mm deep. The chelicerae are used for digging while the body bulldozes the sand out or alternately the hind legs are used to clear the sand. They are difficult to keep in captivity and normally die within 1-2 weeks.

Publications

Dippenaar A. 1993. Sunspiders - some interesting facts. African Wildlife. 47(3): 120-122.
Dippenaar-Schoeman A, Gonzalez Reyers AX, Harvey MS. 2006. A check-list of the Solifugae (sun spiders) of South Africa (Arachnida: Solifugae). African Plant Protection 12:70-92.
Harvey MS. 2003. Catalogue of the smaller arachnid orders of the world. CSIRO Publishing, Australia.
Klann AE. 2009. Histology And ultrastructure of Solifuges - comparative studies of organ systems of solifuges (Arachnida, Solifugae) with special focus on functional analyses and phylogenetic interpretations. link
Punzo F.1998. The Biology of Camel-Spiders (Arachnida. Solifugae). Kluwer Acedemic Publishers.301pp.