Africa Wild

Family Araneidae (Orb-web Spiders)

The family Araneidae has a worldwide distribution with an enormous diversity of > 2600 species. In South Africa the family is represented by 35 genera and 95 species of which 26 species are endemics. 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.
The genera are very diverse in shape, colour, size and behaviour and are grouped in the following subfamilies Araneinae, Argiopinae, Cyrtarachninae. Cyrtophorinae and Gasteracanthinae.
Araneinae: Arachnura (scorpion-tail spiders); Caerostris (bark spiders); Cyclosa (garbage-line spiders); Cyphalonotus (twig spiders); Hypsosinga, Neoscona, Araneus (hairy field spiders); Pararaneus (spicky hairy field spiders); Nemoscolus (stone-nest spiders); Kilima, Larinia and Lipocrea (grass orb-web spiders); Singa (pajama spiders).
Argiopinae: Argiope (garden orb-web spiders); Argiope trifasciata (banded orb-web spiders); Argiope australis (butter spider or black and yellow banded spider).
Cyrtarachninae: Cladomelea (bolas spiders); Pycnacantha (hedgehog spiders); Paraplectana (lady bird spiders); Aethriscus and Cyrtarachne (bird-dropping spiders).
Cyrtophorinae: Cyrtophora (tropical tent-web spiders).
Gasteracanthinae: Gasteracantha (kite spider); Isoxya (box spiders).

Life style
Web dwellers (typical orb-web); webs usually made in and between vegetation.

Body size
Vary between genera (3-30 mm), (males usually smaller, with distinct sexual dimorphism).

Diagnostic characters
Vary between genera.
Colour: varies from cream to brown to greyish black or brightly coloured; colour allows spider to blend in with environment when resting.
Carapace: variable smooth or with numerous protuberances especially ly in species found on bark.
Eyes: 8 in 2 rows (4:4).
Abdomen: variable, usual as wide as long overhanging the carapace, covered with protuberances or patterns, sometimes elongated.
Legs: not very long, when at rest kept close to body.

Web and retreat
Web: the spider hangs head down in the middle of the orb-web or is found in a retreat close by. The web can be either horizontal or vertical. It consists of bridge lines, radii and a circular area, which are usually made of adhesive threads. The shape, number of radii and position of webs vary between the different genera.
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.
Retreat: some genera construct a tunnel-shaped retreat of silk and plant debris on one side of the web. The spider is then in contact with the web with a signal trip-line.

Habitat
Found in a variety of habitats. Commonly found in Savanna, Nama-Karoo, Succulent Karoo, Fynbos Biomes and open forest.

Behaviour
Most species are nocturnal and procryptic by day resting with their bodies appressed against the substrate. The orb-web spiders have poor vision and locate their prey by feeling the vibrations and tensions of the web. They wrap their prey with alternating movements of their fourth pairs of legs by pulling the silk from the spinnerets and throwing large bands of silk over the prey.
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.

Links: Atlas of the Spiders of South Africa; Biodiversity Explorer

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 Argiope web normally has two zig-zag bands of silk radiating outwards from the hub (centre) to the bottom corners of the web. There may be four of these bands in some species while some juveniles may construct a spiral. These are called stabilimenta and serve various functions; stabilize and strengthen the web, make the web visible perhaps serving as a decoy for birds, or also to reflect ultraviolet light thereby deceiving and attracting insects.
The spider sits head down with its legs positioned in pairs, forming a cross with the two anterior (front) pairs resting on the stabilimenta.
"Argiope" means "silver face" with reference to the silver prosoma and may refer to a Greek mythological person.

Species indigenous to southern Africa:
Argiope anomalopalpis
Argiope aurocincta
Argiope australis
Argiope flavipalpis
Argiope levii
Argiope lobata
Argiope trifasciata

Common Garden Orb Web Spider Argiope australis
Family: Araneidae. Subfamily: Argiopinae

© flying cheetah
Kruger National Park, Mopani area.

Life Style
Sedentary, web-bound.

Description
Argiope australis (25 mm body length) has a scalloped abdomen with yellow and black bands. On the Cape Peninsula some spiders have orange and black bands. Males are tiny, measuring 5.5 mm, and can often be seen in or near the females web. Juvenile females appear to have a more slender build.
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.
Colour: carapace silver-grey and abdomens with wide yellow and bluish-black bands, while the legs are yellow banded or spotted; carapace: frequently flattened; eyes: 8 in 2 rows with the posterior row procurved, lateral eyes widely separated from median eyes; abdomen: the sides of the abdomen with distinct scallops in most Argiope spp.; legs: fairly long and thin with the 3rd pair the shortest.

Web and retreat
The Argiope web normally has two zig-zag bands of silk radiating outwards from the hub (centre) to the bottom corners of the web. There may be four of these bands in some species while some juveniles may construct a spiral. These are called stabilimenta and serve various functions; stabilize and strengthen the web, make the web visible perhaps serving as a decoy for birds, or also to reflect ultraviolet light thereby deceiving and attracting insects.
The spider sits head down with its legs positioned in pairs, forming a cross with the two anterior (front) pairs resting on the stabilimenta.

Distribution
Argiope australis occurs over most of Africa except in forests from South Africa northwards to north-east Africa.

Habitat
Their webs are made in grassland, woodland savanna, thicket, Nama-Karoo and open forest between any vegetation sturdy enough to bear the weight of the web and spider. It is commonly seen from about January to June on its web amongst low base vegetation, within a metre from the ground.

Behaviour
They are active during the day when the spider hangs, head down, at the center of the web.
They use the same web over and over again. Usually every few days the sticky silk dries or becomes torn and is removed and replaced.
When disturbed the spider drops or runs from the web onto the adjacent plants. The stabilimentum probably warn inexperienced birds trying to steal the prey from the spiders web, but due to noxious stimulus of the web which tend to irritates their feathers and eyes, they learn to avoid the webs.
When startled Argiope spp. usually reacts by violently shaking their webs. The male is very small and found on the edge of the web during the mating season in summer.

Prey
A variety of flying and jumping insects are snared in the web.

Reproduction
The female produces an egg cocoon that resembles a small kettledrum. She attaches the egg cocoon that can contain more than hundred eggs to the vegetation close to the web.

Venom
Harmless.

Links: Biodiversity Explorer; Martin R. Filmer: Southern African Spiders: An Identification Guide

Banded Orb Spider Argiope trifasciata
Family: Araneidae. Subfamily: Argiopinae

© BluTuna
Male, Nylsvlei Nature Reserve

Life Style
Sedentary, web-bound.

Description
Argiope trifasciata (15-18/25mm body length) has a finely banded abdomen with thin brown, yellow and silvery-white bands. -carapace silver-grey and abdomens with many transverse lines giving it a banded appearance, while the legs are yellow banded. The body is covered with tiny silvery setae (hairs) that point towards the head of the spider resulting in the shedding of rain as spiders always rest head downwards. It may even satisfy the spiders' water requirements. The tiny male only measures 4-5 mm and is usually over looked.

Web and retreat
Web: they spin a typically orb-web with zigzag white stabilimentum bands radiating from the center. Behind the orb-web they build a barrier web made of a network of irregular threads, which protects the spider from predators.
The barrier web is sometimes sheet-like, concave and almost as large as the orb-web. The webs are built in tall grass in sunny areas and the orientation of their webs, varies seasonally in relation to the midday angle of the sun;
Retreat: no distinct retreat.

Distribution
A cosmopolitan species (worldwide distribution), it occurs over most of southern Africa extending northwards through Africa. It is absent only from Europe.

Habitat
It can be found resting head down on its vertical web amongst the grasses

Behaviour
They are active during the day when the spider hangs, head down, at the center of the web.

Links: Biodiversity Explorer; Martin R. Filmer: Southern African Spiders: An Identification Guide

Genus Gasteracantha

Kite spiders of the genus Gasteracantha 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, with shell like abdomens, 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.
Orb webs are usually high in trees.

Species indigenous to southern Africa:
Gasteracantha falcicornis
Gasteracantha milvoides
Gasteracantha sanguinolenta
Gasteracantha versicolor

Medium-wing Kite Spider Gasteracantha versicolor
Family Araneidae

© BluTuna
Pafuri Picnic Site, Kruger National Park

© BluTuna
With Grasshopper prey.

Description
G. versicolour's abdomen is yellow or white with long spines.
Only the females of this genus have the “spines”; the males are also much smaller.

They are orb weavers, and mostly build their orb webs high between trees or shrubs. They are diurnal and don’t remove their web.

The genus Neoscona is similar to Caerostris 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. The orb-web is constructed at night, shortly after dark. once complete the host will position herself head down at the hub (centre) of the web waiting for prey to fly into the web. Insects are attracted to the window light and it is quite remarkable how the spider knew to select such an unnatural but useful site. At the first sign of sunrise, or be fooled at the rise of a full moon, the spider will remove its web only leaving the bridge line and a few supporting threads for construction next evening. Neoscona will be found resting under the gutter during the day. As the common name implies these spiders occur in the veld among grasses and bushes. There are 14 species known from South Africa.

Species indigenous to southern Africa:
Neoscona alberti
Neoscona angulatula
Neoscona blondeli
Neoscona chiarinii
Neoscona hirta
Neoscona kivuensis
Neoscona moreli
Neoscona penicillipes
Neoscona quadrigibbosa
Neoscona quincasea
Neoscona rufipalpis
Neoscona subfusca
Neoscona theisi theisiella
Neoscona triangula
Neoscona vigilans

Green Hairy Field Spider Neoscona rufipalpis
Suborder Araneomorphae. Family Araneidae. Subfamily Araneinae

© steamtrainfan

© steamtrainfan

© steamtrainfan
© steamtrainfan
Garden in Gauteng

Description
Hairy spider with greenish abdomen. Its color changes from a juvenile bright green, to a greyish-green or greyish-brown, to an adult dark brown.
The web is small, loosely woven, with retreat to one side. Spiral silk is usually golden, strong and very sticky.

Distribution
Botswana, Cameroon, Cape Verdi, South Africa, St Helena, Tanzania, Togo, Yemen.

Common Hairy Field Spider Neoscona subfusca
Suborder Araneomorphae. Family Araneidae. Subfamily Araneinae

© BluTuna

© BluTuna
Garden in Johannesburg.

Description
Hairy brown spider. Its abdomen is wider than long.
Prosoma yellow to brown, covered with white hairs. Sternum light in the middle and darker along margins. Chelicerae with 3-4 denticles on promargin and 3 denticles on retromargin. Legs dark brown with light annulations. Opisthosoma: dorsum light, with folium-like pattern (variable), venter black, bordered with white and 2 white spots close to the spinnerets.
Body length male: 4.1-6.2 mm. Body length female: 5.4-11.2 mm.

Distribution
Wide throughout the Afrotropical Region, it is widespread in South Africa.

Habitat
Orb webs are made at night in vegetation and removed in the early morning. This species is common in grassland and low vegetation.

Genus Pararaneus

Spiky Field Spiders resemble Neoscona species but have more and stronger spines, especially the male. Size of Pararaneus spp is 5 to 20 mm. Colour varies from brown to fawn or reddish. The abdomen is shield-like and dorsally rounded, in some species there is a pair of small white spots and in most species there are four or five transverse bands on the abdomen. The moderately long legs are the same colour as the carapace and bear strong spines, especially in males. 8 eyes in 2 rows (4:4) on tubercles; the anterior protruding eyes are especially significant in males.

Spiky Field Spiders construct two types of webs: Adults make a typical vertical orb web. The immature spiders make a horizontal web with a defective frame. It is cone shaped with threads pulling the hub pulled up by guy threads, which are attached to the vegetation above.

Species indigenous to southern Africa:
Pararaneus cyrtoscapus
Pararaneus perforatus
Pararaneus spectator