The Giant Wood Spider Genus – Nephila (araneomorph spiders) Location – Wayanad, Kerala, India Date – August 2014 The golden silk orb-weavers (genus Nephila) are a genus of araneomorph spiders noted for the impressive webs they weave. Nephila consists of numerous individual species found around the world. They are also commonly called golden orb-weavers, giant wood spiders, or banana spiders. The genus name Nephila is derived from Ancient Greek, meaning fond of spinning. Nephila spiders vary from reddish to greenish yellow in color with distinctive whiteness on the cephalothorax and the beginning of the abdomen. Their contrast of dark brown/black and green/yellow allows warning and repelling of potential predators to whom their venom might be of little danger. Golden orb-weavers reach sizes of 4.8–5.1 cm in females, not including legspan, with males being usually 2/3 smaller. Nephila spiders are the oldest surviving genus of spiders, with a fossilized specimen known from 165 million years ago. The name of the golden silk orb-weavers refers to the color of the spider silk, not the color of the spider itself. Yellow threads of their web shine like gold in sunlight. Xanthurenic acid, two quinones and an unknown fourth compound contribute to the yellow color. Experimental evidence suggests that the silks color may serve a dual purpose: sunlit webs ensnare bees that are attracted to the bright yellow strands, whereas in shady spots the yellow blends in with background foliage to act as a camouflage. The spider is able to adjust pigment intensity relative to background light levels and color; the range of spectral reflectance is specifically adapted to insect vision. The spider will remove and consume the portion to be replaced, build new radial elements, then spin the new spirals. Golden Orb Weavers are known to occasionally eat prey as big as small birds and even snakes. Nephila seem to prefer more open habitat such as second-growth scrub or forest edges. The venom of the golden silk orb-weaver is potent but not lethal to humans. Device – Nikon D3x + Lens – Nikon AF-S 400mm f/2.8G ED VR AF + Focal Length 400mm + Aperture – F/3.5 + Shutter Speed – 1/125s + Exposure Mode – Manual + Metering – Matrix + ISO – 800
Posted on: Sun, 31 Aug 2014 06:54:43 +0000
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