Back to photostream

Trichonephila clavipes - Golden Silk Orbweaver / Banana Spider / Aranha-de-Teia-Amarela (Linnaeus, 1767)

Pooping Gold

 

Description: Previously known as Nephila clavipes, Trichonephila clavipes is a spider in the class Arachnida, order Araneae, suborder Opisthothelae, infraorder Araneomorphae, superfamily Araneoidea and family Nephilidae.

 

T. clavipes's abdomen is dark with many irregularly-patterned white punctuations giving it a clear look. Females may have from 24 to 76mm (requires confirmation) in length, while males measure around 8mm, less than, or less commonly, 25mm (requires confirmation). Body larger than width with a legspan of around 152mm. Eye disposition at 4 to 4. Median posterior eyes possess a tapetum. Body is cylindrical.

 

The legs are banded and alternating between darker parts and orangeish-red, with tufts of hair (gaiters) on the tibial segments 1, 2 and 4, and curving down at the tip. Males are typically dark brown, slender spiders. Females make at least two large eggsacs with 25 to 30mm in diameter consisting of several hundred eggs. The eggsacs are surrounded by curly yellow silk. During their reproductive season, males will search for females and get on their web. Males challenge each other for the position closest to the female, the largest becoming her mate. Smaller males go to the edges of the web. Mates gain the almost exclusive advantage in mating as well as feeding on prey caught by the female's web. The males around the edges may try to mate with the female but rarely accomplish this. Occasionally, the female will feed on the males.

 

They are aerial orb-weavers which web displays a yellow / golden coloring which gives them their vernacular name. Webs can reach over 900mm in diameter (or length?) at eye vision level or above forests and mangroves. Webs have been seen measuring 4 meters in diameter (or length?). The orbicular web woven between branches of trees is carefully sculpted in strong strings of golden silk which are intertwined and reinforced at the center in a zigzag shape (stabilimenta), in a height where insects generally fall prey. The webs are also symmetric with an asymmetrical orb near the top where the the spider dwells. The orbicular web is so strongly woven that even small birds may fall prey, which is not uncommon to happen. In fact, the silk is so sticky that they are known for their incredible resistence, being compared to steel cables in a proportional sense. Prey includes Diptera, Hymenoptera, Lepidoptera, Coleoptera, Odonata and, as previously mentioned, occasionally small birds. The web is a semipermanent structure, which means they are not destroyed and created periodically like other members of Araneae. They usually repair damaged web structures.

 

Like most spiders, they are venomous but their venom is weak and is not a threat to humans, unless they are allergic to the venom. Otherwise, they are harmless and will only bite if held or pinched. The bite leaves simple swelling, redness and localized pain. The bite is, theoretically, less dangerous than a bee sting. They are widely distributed in Australia, Asia, Africa, Argentina, Madagascar, South America é North America to the South of the USA. They can be seen all over Brazil but their habitat is the Atlantic Forest, forest edges and dense woodlands.

 

T. clavipes are often found on banana trees. They live under hot weathers; this made them develop structures to prevent them from overheating. Such structures include the silvery carapace that reflects sunlight, while the long and cylindrical body reduces the area of the exposed body by being pointed directly at the Sun. They can also force evaporative cooling by dropping a fluid with the chelicerae; this is generally done when temperatures are higher than 35°C (Krakauer, 1972). Webs are woven regardless of Sun position, with the aim of capturing as much prey as possible. Their orientation movements can be complex (Robinson and Robinson, 1974). They are not aggressive and will rarely leave their webs. They will change colors as they mature. In the picture we can see an adult female and an adult male behind.

 

The silk in the center of the web possess oily drops which contain vesicles that trap proteic and peptidic solutions inside, as well as many composts of low molecular mass. The drops contain toxins, saturated fatty acids and even alkaloids. It is speculated that these saturated fatty acids help to destabilize the cuticles of the insect and allow the diffusion of the toxins to the interior of the body. This study proves that their webs are not purely for mechanically ensnaring prey, but a very complex structure with an active role on the capture of prey. Seemingly, repellent alkaloids to some predators are seen in a few webs, as well as insect toxins in others. The silk glands, especially the aggregated gland, can synthesize and deposit over the silk important toxins which are common to a few animal toxins, putting them on a higher step in the food chain compared to some spiders.

 

repositorio.unesp.br/bitstream/handle/11449/150381/esteve...

 

According to the following study, they can adapt well to abandoned webs that belong to other spiders:

 

"The experiments showed that both resident spiders and introduced spiders remained in the webs in which they were placed. Resident females demonstrated that, when they were bigger, they showed an advantage in the dispute against the invasive (introduced) species, though it was not noticed any significant advantage when the "invasive" (introduced) individuals had the same size or were bigger. The resident invested more in the maintenance of the web than the "invasive" (introduced), performing more agonistic behaviors and returning more times to the web after combats. It did not occur intolerance among individuals on the support wires, thus indicating that the formation of aggregations might be related to the tolerance of individuals to accept the presence of conspecifics from nearby areas." - repositorio.ufjf.br/jspui/bitstream/ufjf/5567/1/biancapoc...

 

Other sources:

 

www.ninha.bio.br/biologia/nephila.html

 

faunaefloradorn.blogspot.com/2010/07/aranha-de-teianephil...

 

www.achetudoeregiao.com.br/animais/nephila_clavipes.htm

 

professora-mel.blogspot.com/2013/01/foto-da-aranha-que-es...

 

entnemdept.ufl.edu/creatures/misc/golden_silk_spider.htm

 

bugguide.net/node/view/2023

 

pt.wikipedia.org/wiki/Nephila_clavipes

 

en.wikipedia.org/wiki/Nephila_clavipes

 

eol.org/pages/1193392/overview

 

PROJECT NOAH (Português): www.projectnoah.org/spottings/1003890997

7,885 views
11 faves
1 comment
Uploaded on August 25, 2018
Taken on March 4, 2017