Homeward bound (62)
|Banded-legged golden orb-web spider|
Nephila senegalensis annulata
Golden orb-web spiders belong to the family Tetragnathidae, subfamily Nephilinae. There are two genera: Nephila (Golden orb-web spiders) and the monophyletic genus Nephilengys (hermit spiders). There are three species in the genus Nephila: Nephila pilipes fenestrata (black-legged golden orb-web spider), Nephila senegalensis annulata (banded-legged golden orb-web spider) and Nephila inaurata madagascariensis (red-legged golden orb-web spider).
These large, obtrusive spiders are one of the few spiders which can be identified down
to species without the aid of a microscope and a fancy key. They are strictly web bound and find walking on the ground cumbersome. Nephila construct very large orb webs, often between trees or bushes from 1.5m to 6m above the ground. (I have posted a WS with the photo of the whole web.) Their silk is golden in colour and extremely strong. There are trip lines around the web and quite often prey remains are strung up to form a line through its centre. Their slightly angled webs are designed to catch large flying insects and small birds are occasionally snared, but rarely eaten. The female spider hangs inverted in the centre of the web, while one or more males lurk on the periphery of the web. Males are many times smaller than the females and can be distinguished by their swollen pedipalps which are similar to boxing gloves. It has the widest distribution throughout South Africa.
Reproduction is similar for all Nephila. As in the case of Nephila senegalensis annulata, the male (he can be seen just below the female in the photo) spins a small sperm web onto which he deposits a drop of sperm which he sucks up into his pedipalps. He will usually only approach the female when she is otherwise occupied i.e. feeding. He descends towards her and inserts his pedipalps, one by one, into her genital opening which is situated underneath her abdomen. Copulation may take as long as 15 hours and afterwards the now exhausted male retreats to a safe place away from the female. When ready to lay her eggs, she selects a suitable site and constructs an egg sac using special loopy white silk. After a fortnight or so, the young spiders hatch inside the eggsac. At this time they are still embryonic living off the yolk. Their mouthparts, venom glands, digestive tracts and spinning organs are underdeveloped, and only after the yolk has been absorbed and their body parts are properly developed do the spiderlings cannibalise each other and must disperse. Their life history follows a yearly cycle with the females living slightly longer than the males.
These large, shy but beautiful spiders may look formidable but are not aggressive, and even those who walk into their webs are unlikely to be bitten and although their bite is painful, it is not of great medical importance. Hope you like it.