Family: Araneidae (orb-web spiders)

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

In South Africa the family Araneidae includes 40 genera of master weavers. This is one of the families referred to as the orb-web spiders (another being, Tetragnathidae) although some genera do not spin orb webs. The Greek myth about Arachne is probably attributed to one of these spiders. This is one of the most diverse groups of spiders with various shapes, colours and camouflage systems. They are harmless to man.

There are both diurnal (day) and nocturnal (night) species. The diurnal groups continually repair their webs, usually using them for a number of days. The web cannot be used indefinitely as it dries and loses its capture ability and insects will no longer stick to it. Nocturnal spiders, on the other hand, construct a new web every night and it is taken down at dawn and eaten. This serves as a valuable source of protein. The bridge line, the main original stay that is built, is retained for reuse. The webs consists of a bridge line with a frame and supporting threads, numerous radials, a viscid (sticky) spiral and a central hub which may be open or matted with silk. Webs may be vertical, inclined and rarely horizontal. Each species of spider has its own characteristic web design.

The Araneidae (with the family, Tetragnathidae) occupy a niche not utilized by other spiders. They occupy the aerial passage amongst vegetation in the path of flying insects. The spider sits on the web waiting for prey to get trapped in the web. Once prey is caught, the spider then cautiously approaches the prey, wraps it in silk to immobilize it and kills it with a venomous bite. The prey is then moved to the centre of the web or to its retreat among vegetation and consumed. As spiders cannot eat solids, the internal organs have to be liquidised. The spider pumps enzymes from its mouth through the fang puncture holes to create a soup which it can drink. This action differs from the Tetragnathidae.

Genera indigenous to southern Africa

Arachnura (scorpion-tailed spiders)

The name is derived from Greek "arachne" means "spider" and "ura" means "tail", referring to the likeness of the end of the abdomen to a scorpions tail. One species in Africa: Arachnura scorpionoides.

Araneus (hairy field spiders)

Not easily separated from Neoscona or Pararaneus. There are 16 species listed for South Africa.  The orb-web, with the hub 0.8-2.8 m above ground level, has a diameter of 50-200mm and a free sector of 20-25% of the web. From the hub to the spider's retreat runs a "telegraph line" that informs the spiders of any prey caught in the web.

 

Argiope (garden spiders)

Argiope is one of the most familiar genera of orb web spiders. Being diurnal, garden spiders are colourfully marked, the carapace silver and the legs banded. The aposematic (warning) yellow and black colouration of the abdomen remind birds that they are unpalatable. The web normally has two zig-zag bands of silk called stabilimenta radiating outwards from the hub (centre) to the bottom corners of the web. The spider sits head down with its legs positioned in pairs, forming a cross with the two anterior (front) pairs resting on the stabilimenta.

 

Caerostris (bark spiders)

Bark spiders are nocturnal orb-web spiders that construct a large orb web, up to 1.5 metres, stretching from one tree to the next. The abdomen is cryptically coloured and adorned with numerous horny projections and viewed from the rear a definite animal face can be perceived. When she is off her web she retires to a branch and packs her legs tightly next to her body and she melts into her surroundings looking like a knot on the branch. They are large spiders with females reaching 30mm, body length. Very few males, which are tiny, have been collected.

 

Cyclosa (garbage line spiders)

A diurnal genus with three species known from South Africa. Normally Cyclosa can be found in its web in grass or among the branches of bushes but also in nurseries and fences. This is a small 5-11mm spider with an elongated abdomen ending in one to four tubercles. The vertical orb-web measures about 150mm across and consists of many tightly woven radii and spirals. The stabilimentum of this spider's web runs vertically or occasionally horizontally through the hub and is decorated with the remains of prey, the spiders exuvia and bits of debris. The numerous egg sacs are usually incorporated into the stablimentum. At the hub the line is parted and the spider sits hidden amongst the debris.

Cyrtophora (tent-web spiders)

The only species of the genus Cyrtophora in South Africa is the cosmopolitan tropical tent-web spider, Cyrtophora citricola. The web of this species is a-typical, in that it is similar to mesh curtaining, which forms the orb section of the web, and the spider spends both day and night on it. The orb-web is supported by numerous knock-down threads that form a tent, and these deflect prey onto the orb-web.

Gasteracanthus (kite spiders)

Kite spiders are diurnal orb-web spiders. Species occur mainly in the tropics and sub-tropics, with four species in South Africa. The spider is small, 8-10 mm, brightly coloured in shades of cream, yellow, red and black. The adbomen is sclerotised (porcelain-like) with four lateral and two posterior spines, the second pair longest and the first shortest.

Gea

Closely related to Argiope. These two genera belong to the subfamily Agriopinae. Four species occur in Africa with Gea infuscata the only species found in South Africa. Not much is known about its distribution or ecology. The orb-web is placed among low base vegetation or grass and can be found with or without a stabilamentaum.

 

Isoxya (box kite spiders)

Isoxya, the Box kite spiders are small spiders, 3-7mm body length, with the typical sclerotised (porcelain-like) abdomen of the Gastricanthinae with four lateral and two posterior short spines. There are 6 species of these orb-web spiders found in South Africa.

Larinia (grass orb-web spiders)

Larinia are small, 4.5-7.5mm, nocturnal  spiders and can be found in their orb-webs in long grass. The webs are constructed at night and removed again at first light next morning. The abdomen varies from oval to elongated, always longer than wide often marked with longitudinal dorsal stripes or bands. Larinia can be found on all continents, except Antarctica, with seven species in South Africa.

 

Neoscona

Similar to Caerostris in being nocturnal and cryptically coloured. It is also referred to as the hairy field spider and has a globose (round) abdomen which overhangs the carapace. The legs are equipped with numerous spines. During the day this spider takes refuge amongst leaves and in or under bark. Neoscona species are very variable in colour. This is the spider responsible for the mysterious orb web found spanning from gutter to balustrade at night only to be missing next morning. There are 14 species known from South Africa.

Nemoscolus  (stone-web spiders)

The stoneweb spider is seldom seen as it retreats inside a small conical to helicoid shelter positioned above the centre of its cone-shaped web, which opens downwards onto its horizontal web. The shelter is at the hub of the web and is pulled up and attached to some grass or other vegitation. The common name can be somewhat missleading as the retreat can be constructed with any available particles such as sand, plant matter woven into silk. This retreat will also house the eggs and young.

 

Paraplectana (lady bird spider)

 

Pycnacantha (hedgehog spiders)

A genus of spiders that has an abdomen with numerous projections, hence the common name. Pycnacantha has, as with numerous other araneids, abandoned life in orb-webs and hang head down with front legs outstretched to capture flying moths. Pycnacantha tribulus is the only known South African species. Pycnacantha dinteri the only other southern African species occurs in Namibia.

 

Text by Norman Larsen .


Contact us if you can contribute information or images to improve this page.

 Arachnids home   Biodiversity Explorer home   Iziko home   Search