The golden silk spider (formerly known as Nephila clavipes) is an orb-weaving species which inhabits forests, marshes, and woodlands on both continents; it is the only species of its genus native to continental North and South America. This spider constructs circular webs attached to trees and low shrubs in wooded areas to catch small- and medium-sized flying prey, primarily insects. It is known for its golden silk, their large size, and their distinctive red-brown and yellow coloring. Unlike related species that initially immobilize their prey by wrapping them in silk, these species build webs by using seven kinds of silk and injecting venom into their prey, which is stronger than wrapping their prey in silk first. There is no evidence that these snakes are aggressive toward humans, and they only bite as a form of defense if they are threatened, and their venom is relatively harmless, so healthy adults have little need to worry about it. T clavipes are commonly found in forests, which makes them accessible to hikers.

Golden silk orb-weaver Spider


In addition to its larger size and more complex coloration, T. clavipes also shows sexual dimorphism, with its females having a larger and more impressive appearance. In comparison, males of other species of the subfamily Nephilinae are exposed to sexual cannibalism and genital mutilation at a higher rate than those of T. Studying the mating behaviors of spiders is a focus of the study of clavipes. There is a preference in most environments for polygyny in the species, although individuals can result in both monogyny and polygyny.

Spider silk research makes T clavipes an important species with a high recognized value to humans. Scientists have discovered 28 unique genes for spidroins, the proteins that comprise spider silk, in the genome of this species, the first of the orb-weaving spiders to be completely annotated. In addition, T clavipes silk has been proved capable of aiding in surgery involving the nervous system in past experiments.


This species has a marked dimorphism in size as well as color pattern, similar to most orb-weavers. The female T clavipes ranges in size from 24 mm to 40 mm when it is fully developed, which makes it one of the largest spiders in North America. Some believe they are the largest species of U.S. orb weaver. The species is relatively easy to identify because of the very distinct coloring of the females. The cephalotorus is silvery and has a long orange-brown abdomen with white-yellow spots in two rows. The color of the spider's abdomen changes as it matures. Dark yellow and brown bands cover their legs, and they also have brush-like tufts of hair on their first, second, and fourth legs.

A male zebrafish measures around 6 mm in length, and is about one-third or one-quarter as long as a female. It also has a much slenderer build than a female. An adult female of that size is roughly 1/30th as large as a small male. Males, on the other hand, have dark brown bodies and legs and much less complex colouration. In males, a black band is found on the tibial segment near the end, in the same area as the tufts of black hair on a female.  

Often confused with Trichonephila plumipes, T clavipes has similar stiff hairs on its legs as its congener. In T plumipes, however, the hairs are nearly as closely packed together as those of T clavipes.

 
Golden silk orb-weaver

  • Common name - Golden silk-orb weaver
  • Latin name - Trichonephila clavipes
  • Also known as - Banana spider
  • Venomous - Mild, comparable to a bee sting
  • Range - North, Central and South America
  • Size -  Body length: 0.31 to 2 inches (8 to 50 mm)
  • Unique feature - Clumps of dark hair on legs

Golden silk orb-weaver Behavior


These coloured spiders receive their name from the color of their silk, rather than from the spiders themselves.


When the sun shines, their yellow web threads sparkle. An unknown fourth chemical compound, xanthurenic acid, contributes to the yellow color. In terms of research, it seems that the yellow hue of the silk may serve a dual purpose: in the sun, the yellow attracts bees, while in the shade, the yellow blends in with surrounding foliage as a camouflage. An insect's eyesight is specifically adapted to reflect spectral reflectance based on background light levels and color.


A Nephila spider's web typically consists of a fine-mesh orb suspended in a maze of non-sticky barrier webs. Apparently the stickiness of these orbs declines with age, as it is renewed regularly if not daily by weavers who weave sticky spirals. In good weather (without rain damaging the web), subadults and adults are often unable to rebuild the entire web. By removing and consuming the component to be replaced, building new radial elements, and spinning the new spirals, the spider will create new elements. Other orb-weaving spiders renew their entire orb webs at once, unlike this partial orb renewal. A 2011 study discovered chemicals in Nephila antipodiana's web that repel ants.


As the spider grows bigger, the density of sticky strands in the spiral decreases (the density of sticky spiral strands depends on spider size). She fills in the gaps once the coarse weaving is complete. When spinning the sticky spiral, Nephila does not remove the non-sticky spiral. The result is a "manuscript paper" effect when viewed in the sun: groups of sticky spirals reflecting light with "gaps" within the non-sticky spirals.


N clavipes webs are sometimes more than a meter in diameter, with support strands reaching out for many miles. A spider's web may extend from eye-level up into the tree canopy in relation to the ground. A horizontal support strand usually truncates the orb web, giving it an incomplete appearance.


There may be a network of guard-strands on one side of the main orb that appear rather haphazardly suspended a few inches apart across a small area of open space. Frequently, this network is embellished by string or two of plant detritus and insects clumped with silk. This "barrier web" may be used to warn predators of incoming prey, to shield against wind-swept leaves, or as a way of alerting the owner of the incoming prey. Birds can avoid blundering into the web and destroying it when they perceive the suspended debris-chain as a cue.


N clavipes have stabilmenta in their webs just before they molt, for which they are known as "molting webs" or "skeleton webs" (webs with radial strands, but no spirals).


Mechanisms for capturing prey


In order to allow strong wind to flow through the web without breaking it, the golden silk orb weaver (Nephila edulis) disassembles the lower part of its web on windy or rainy days. Prey as large as birds and even snakes as well as small fish is eaten by Golden Orb Weavers.


The non-parasitic Argyrodes spider, usually very small black-and-silver spiders, is often found attacking N clavipes (and many other species of Nephila). Nephila webs may have up to a dozen spiders infesting them to feed on prey captured by the host spiders. 

Argyrodes may be controlled by Nephila by rebuilding or abandoning webs frequently. Food is also obtained through the webs of Nephila by spiny orb-weavers.


Golden silk orb-weaver Llife cycle


The spiderlings


Spiders under the age of two usually do not build yellow silk, and young Nephila look broadly similar to young Orchard Spiders (Leucauge) (both species have silver stripes or patches on their abdomens, thought by some to act as heat sinks). Nephila and Leucauge juveniles are primarily distinguished by their web structure: Leucauge builds horizontal orbs that are perfect circles, while Nephila build vertical orbs that are incomplete (missing a portion of the orb that surrounds the spider). The nephila prefers places with a lot of open space, such as scrubby second-growth or forest edges. Overhangs of buildings or fences are also useful.


When approached by a predator, young spiders also exhibit vibrational motion. A potential predator's plowing of the web will cause the spiders' webs to oscillate at around 40 Hz. During an attack by a predator, the spider escapes through one of three routes: on a silk line that floats along the web, or by jumping off the web after oscillations in the web facilitate jumps.


Golden silk orb-weaver Human interaction


There does not appear to be a beneficial or harmful relationship between these spiders and humans. They might cause problems for gardeners or flower pickers because their webs are woven in bushes and around flowers. There are some nests that can deter known pests, like fruit flies, without the need for insecticides.


Golden silk


Several attempts have been made in the past to produce garments from Nephila silk, but none of them were successful. A pair of bed hangings was the last garment to be produced for the 1900 Paris Exhibition. As recently as 2009, Simon Peers and Nicholas Godley used 1.2 million Golden silk orb weaver (collected in the field and released about 30 minutes after they produced the silk) to produce a shawl that was exhibited at The American Museum of Natural History. Two garments were made by 2012, a cape and a shawl, that were displayed at the Victoria and Albert Museum in London.


Tissue engineering is another possible application of Nephila silk. The Medizinische Hochschule Hannover reports that processed Nephila silk is a useful scaffold material because it improves cell adhesion and proliferation through its biocompatibility, mechanical strength, and biocompatibility. Particularly, silk can guide regrowth of peripheral nerves.


Fishermen throw balls of Nephila web into the Indopacific Ocean after removing the webs from the coast. In this way, bait fish can be caught with it.


Toxins and glands

Silk glands

The orb-weaving spider species produce silk from seven different types of silk glands. The female T clavipes possesses all seven types of silk glands. It has (i) major ampullate, (ii) minor ampullate, (iii) piriform, (iv) aciniform, (v) tubuliform, and (vi) flagelliform, and (vii) aggregate. Featuring high tensile strength, major ampullate silk is used for radii, draglines, and bridgelines. When the web is built, ampullate silk is used as scaffolding, and piriform silk is used like cement for bonding fibers together. As with major ampullate silk, aciniferous silk is strong, but it is flexible as well, making it perfect for wrapping prey and insulating eggs. During prey capture, the flagelliform and aggregate silks confer extensibility and stickiness to the tough outer shell of egg cases. Spider fibroin proteins, or "spidroin," differ in their composition in these silks.

A single thread of the anchor silk has a tensile strength of 4×109 N/m2, which exceeds that of steel by a factor of eight (ultimate strength of steel 500x106 N/m2). T clavipes silk, especially in the draglines, exhibits exceptional thermal conductivity, surpassing most metals, according to research conducted by Iowa State University.

Phylogeny

The golden orb-weaving spider family Nephilidae is sometimes referred to as Trichonephila clavipes. Other researchers have discarded Nephilidae in favor of Nephilinae, a subfamily within the Araneidae family, and assigned all golden orb-weaving spiders to it. T. Nephila and Nephila have now been added to the Nephilinae subfamily, following recent phylogenetic studies. Its current assignment is Trichonephila, to which the Clavipes originally belonged. Trichonephila has the most species of all the Nephilinae genera.

Golden silk orb-weaver Toxicity

Humans cannot be killed by the venom of the golden silk orb-weaver. Although black widow spider venom is powerful, its neurotoxic effect is similar to that of this spider. Blisters and pain from the bite usually disappear within 24-hours. Rarely, it could cause allergic reactions, breathing difficulties (in asthmatics), or rapid contractions of muscles. Hard tissues (such as fingers) may be left with long-lasting scarring from the genus' chelicerae, which are fairly strong.