Nephila pilipes

Tadoba Andhari Tiger Reserve, Pench National Park, Tipeshwar Wildlife Sanctuary & Pulau Ubin

I remember a time in August 2018 when I had gone for a trek to Pulau Ubin and as I walked the island in search of birds I stopped suddenly in my tracks and closed my eyes. An involuntary reaction on my part to an unexpected encounter. I slowly opened my eyes, as I cleared from my face, the gigantic spider web I had walked into.

I must have walked into any number of spider webs a multitude of times as I wandered the jungles searching for birds and wildlife. But this time was different – the web was particularly sticky. After clearing the web from my face and body, I stepped back to see whose web I had inadvertently destroyed. It was the all familiar Giant Wood Spider - Nephila pilipes - also called the Giant Golden Orb Weaver. This giant spider is one of the larger spiders belonging to the genus Nephila consisting of numerous species found in warmer regions around the world. I realised, after this close encounter, that their web is actually yellow and not white as one would normally expect. This is what gives them their moniker - Giant Golden Orb Weaver.

The name Giant Wood Spider is used to refer mainly to Nephila pilipes, which is very often seen, given its size and the size of its web. This is a common spider in the jungles of peninsular India and across the moist jungle of South Asia, where webs built across large open spaces (and at times spanning up to 2 meters) are not uncommon.

Pulau Ubin

Nature and history intertwine effortlessly on Pulau Ubin. Located off Singapore’s north-eastern coast, a 15-minute bumboat ride from Changi Point Ferry Terminal, this tranquil island sanctuary is a popular haunt of nature lovers and day trippers unwinding from the bustle of the city. Originally known as Pulau Batu Jubin (Granite Stone Island in Malay), this 1020-hectare island’s granite quarries once provided the stone used to construct structures like the Istana and the Singapore-Johore Causeway. The name Pulau Ubin literally meaning "Granite Island" in Malay, explains the many abandoned granite quarries there. Pulau means "island", and Ubin is said to be a Javanese term for "squared stone". To the Malays, the island is also known as Pulau Batu Ubin, or "Granite Stone Island". The rocks on the island were used to make floor tiles in the past and were called Jubin, which was then shortened to Ubin. The island is known as tsioh sua in the Taiwanese Romanisation of Hokkien, which means "stone hill". The highest point is Bukit Puaka (Haunted Hill in Malay) at a height of 75m and legend has it that Pulau Ubin was formed when three animals from Singapore (a frog, a pig and an elephant) challenged each other to a race to reach the shores of Johor. The animals that failed would turn to stone. All three came across many difficulties and were unable to reach the shores of Johor. Therefore, the elephant and pig together turned into Pulau Ubin whilst the frog became Pulau Sekudu or Frog Island.

Pulau Ubin, also simply known as Ubin, is situated in the north east of Singapore, to the west of Pulau Tekong and first appeared in an 1828 sketch of the Island of Singapore as Pulo Obin and in Franklin and Jackson's map as Po. Ubin. Since the British founding of Singapore, the island has been known for its granite and the quarries used to be supported by a few thousand settlers on the island in the 1960s. These numerous quarries supplied the local construction industry. Today the granite outcrops are particularly spectacular from the sea because their grooves and fluted sides create furrows and ridges on each granite rock slab. These features are captured in John Turnbull Thomson's 1850 painting — Grooved stones on Pulo Ubin near Singapore. The granite from Pulau Ubin was used in the construction of Horsburgh Lighthouse. Tongkangs ferried the huge rock blocks (30 by 20 feet) from the island to Pedra Branca, the site of the lighthouse, in 1850 and 1851. Later, the granite was also used to build the Singapore-Johor Causeway. Most of the quarries are not in operation today and are being slowly recolonised by vegetation or filled with water. Apart from quarrying, farming and fishing were the principal occupations of the inhabitants of the island in the past. It is also called Selat Tebrau (tebrau is a kind of large fish). In the 1970s as the granite quarries closed down and jobs dwindled, residents began leaving and only about 40 villagers remained as of 2012.

As are most islands in this region, Pulau Ubin also is an emerald island with a multitude of habitats, from seagrass lagoons to mangroves teeming with wildlife. Given its size walking the island is a fairly daunting task and to make it easier bikes can be rented from near the jetty. Heading along the eastern trail one is led to the spectacular Chek Jawa Wetlands - an ecosystem created by the confluence of six distinct habitats - coastal forests, rocky beaches and a mangrove swamp. There are fiddler crabs, red jungle fowl, mudskippers, wild boar and many more. An erstwhile quarry - Pekan Quarry - located a 15-minute walk away from the jetty, is now a beautiful lake, surrounded by lush greenery and home to otters, dragonflies and various species of birds.

Pulau Ubin is one of the last rural areas to be found in Singapore, with an abundance of natural flora and fauna. The island forms part of the Ubin–Khatib Important Bird Area (IBA), identified as such by BirdLife International because it supports significant numbers of visiting and resident birds, some of which are threatened. Today, the island is managed by the National Parks Board, compared to 12 agencies managing different areas of the island previously.

Rukhad, Pench National Park

Pench National Park, nestled in the heart of India in the lower southern reaches of the Satpura hills, sprawls a massive 758 km² across the states of Madhya Pradesh & Maharashtra. In Madhya Pradesh it is located in the districts of Seoni and Chhindwara. Named after the pristine River Pench it was immortalised by Rudyard Kipling in his Jungle Book. Every year millions make their way here to spot Akela (the Indian Wolf), Baloo (the Sloth Bear), Bagheera (the Black Panther) and Shere Khan (the Royal Bengal Tiger). It was declared a sanctuary in 1965 and elevated to the status of national park in 1975 and enlisted as a tiger reserve in 1992.

Pench has a glorious history of natural wealth and unique cultural richness described in several classics ranging from the Ain-e-Akbari to the Jungle Book. Several natural history books like Strendale’s “Seonee - Camplife in the Satpuras” & Forsyth’s “Highlands of Central India” present a detailed panorama of these forests. 

The forest, lush and green in the monsoon, also harbours a wide range of faunal species some of which figure prominently in the IUCN Red List.

The small hills and well-stocked teak mixed forest of Rukhad are slated as the buffer zone and a part of the Pench-Kanha and Pench-Satpura Corridors, Rukhad used to be the hunting grounds of the British. With Granite & Gneiss as the main rock types, the area is filled with unique habitats like Snags, Nesting sites, Cliffs, Overhangs, Talus, Dens, Caves and natural salt licks - prime tiger habitat. 

The park also was the location used by the BBC for the innovative wildlife series Tiger: Spy in the Jungle, a three-part documentary narrated by Sir David Attenborough which used concealed cameras, placed by elephants, in order to capture intimate tiger behaviour and also retrieved footage of various other fauna in the reserve. The programme aired for the first time in March 2008 and ended a month later.

Like all other forests in India tigers coexist with other predators such as leopards, Asiatic wild dogs, brown bears and wolves throughout most of their range. Usually there is little interaction between species especially since tigers are mostly nocturnal (active at night) and the other species are mainly diurnal (active during the day).

Giant Golden Orb Weaver/ Giant Wood Spider

Nephila is a genus of araneomorph spiders noted for the impressive webs they weave. Nephila consists of numerous species found in warmer regions around the world, although some species formerly included in the genus have been moved to Trichonephila. They are commonly called golden silk orb-weavers, golden orb-weavers, giant wood spiders, or banana spiders.

Nephila spiders vary from reddish to greenish yellow in color with distinctive whiteness on the cephalothorax and the beginning of the abdomen. Like many species of the superfamily Araneoidea, most of them have striped legs specialised for weaving (where their tips point inward, rather than outward as is the case with many wandering spiders). Their contrast of dark brown/black and green/yellow allows warning and repelling of potential predators to which 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 two-thirds smaller (less than 2.5 cm). In 2012, a large individual was photographed killing and consuming a 0.5-m-long brown tree snake in Freshwater, Queensland. Species from Taiwan have been known to reach over 130 mm, leg span included, in mountainous country. In 2014, a study discovered that golden orb-weavers living in urban areas, particularly areas of a high socioeconomic status, grew larger and carried more eggs than those in their native habitats. A number of possible explanations were suggested, such as increased food supplies due to artificial light or lack of predators and parasites.

In 2018, twelve Nephila species were reclassified as Trichonephila, with another two (N. kuhlii and N. robusta) considered in 2020 to be junior synonyms of N. pilipes. Species whose placement has been changed by some sources include:

• Nephila laurinae was considered to be a synonym of Trichonephila antipodiana ("Batik Golden Web Spider"), found most commonly in the Philippines and Vietnam

• Trichonephila komaci, found most commonly in South Africa and Madagascar, transferred from Nephila komaci

• Trichonephila clavipes (or "banana spider") found widely in warmer parts of the Americas, transferred from Nephila clavipes

• Trichonephila inaurata (or "red-legged golden orb-weaver spider") found most commonly in southern and East Africa, transferred from Nephila inaurata

• Trichonephila plumipes (or "tiger spider") found most commonly in Australia, transferred from Nephila plumipes

As of October 2021, the World Spider Catalog did not accept all of these changes, listing the following species in the genus Nephila:

• Nephila comorana (Strand, 1916) – Comoros, Mayotte

• Nephila constricta (Karsch, 1879) – Tropical Africa

• Nephila cornuta (Pallas, 1772) – Guyana

• Nephila dirangensis (Biswas & Biswas, 2006) – India

• Nephila kuhli (Doleschall, 1859) – Myanmar to Indonesia

• Nephila laurinae (Thorell, 1881) – Malaysia to Solomon Is.

• Nephila pakistaniensis (Ghafoor & Beg, 2002) – Pakistan

• Nephila pilipes (Fabricius, 1793) (type*) – India to China, Vietnam, Philippines, Taiwan, Australia

• Nephila tetragnathoides (Walckenaer, 1841) – Fiji, Tonga, Niue

• Nephila vitiana (Walckenaer, 1847) – Indonesia, Fiji, Tonga

Additional fossil species are known from the Cenozoic. In 2012 Geratonephila burmanica was described from the Cenomanian aged Burmese amber, Wunderlich 2015 synonymised Geratonephilia with Nephilia tenuis, a species from the Dominican Amber, as he considered it unlikely that the amber was actually Burmese in origin. Though largely ambiguous, the origins of Nephila are undoubtedly Gondowanan. With the prime candidates being Africa, Indomalaya, and Australasia.

* In zoological nomenclature, a type species (species typica) is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen (or specimens). A similar concept is used for suprageneric groups and called a type genus.

Nephila pilipes (northern golden orb weaver or giant golden orb weaver) is a species of golden orb-web spider. It resides all over countries in East and Southeast Asia as well as Oceania. It is commonly found in primary and secondary forests and gardens. Females are large and grow to a body size of 30–50 mm (overall size up to 20 cm), with males growing to 5–6 mm. It is the second largest of the orb-weaving spiders apart from the recently discovered Nephila komaci. The first, second, and fourth pairs of legs of juvenile females have dense hairy brushes, but these brushes disappear as the spider matures.

The Nephila pilipes golden web is vertical with a fine irregular mesh. It is not symmetrical, with the hub usually nearer the top. Rather than egg sacs being hung in the web, a pit is dug which is then covered with plant debris or soil.

Nine subspecies are recognised:

• N. p. annulipes (Thorell, 1881) – (Indonesia)

• N. p. flavornata (Merian, 1911) – (Sulawesi)

• N. p. hasselti (Doleschall, 1859) – (Java)

• N. p. jalorensis (Simon, 1901) – (India, Sri Lanka)

• N. p. lauterbachi (Dahl, 1912) – (New Guinea)

• N. p. malagassa (Strand, 1907) – (Madagascar)

• N. p. novaeguineae (Strand, 1906) – (New Guinea)

• N. p. piscatorum (Vis, 1911) – (Queensland)

• N. p. walckenaeri (Doleschall, 1857) – (Java)

Nephila pilipes display female gigantism and male dwarfism. In terrestrial animals, They have the most size differences between males and females which can be explained by the evolutionary selection for females with better fecundity. Female N. pilipes have huge parental investments to their progenies, including egg production and web construction. Females typically have a body size of 30–50 mm. The cephalothorax is about 15 mm long, 10 mm wide. The abdomen is about 30 mm long, 15 mm wide, mostly dark yellow-brown color with yellow stripes. The tergum is generally black or brown, covered with dense hairs. Both rows of eyes bulge towards the rear. The plastron is mostly black and brown. The legs span very long, and they are black and yellow. There are no apparent hairs on all legs. It has been reported that this sharp contrast between yellow and black color can increase foraging success towards visually-oriented prey. Males’ body size is typically 5 mm to 6.5 mm. The cephalothorax is about 2.5 mm long, 2 mm wide. The abdomen is about 4 mm long, 1.5 mm wide. Front eyes are larger than rear eyes. Males have light brown legs, with some hairs. The carapace is yellow with very few hairs. N. pilipes has a few different features which make it easy to distinguish from similar species. Unlike Trichonephila clavata, N. pilipes has a horn-like bulge on its tergum. Additionally, it has a pair of yellow stripes at its back of the abdomen unlike Nephilia laurinae. Nephila pilipes display sexual dimorphism, the presence of distinct difference between the males and females of a species. Female spiders are much larger than their male counterparts, and males can be 4–10 times smaller than the females.

N. pilipes prefers moist habitats with no direct sunlight. It is found in Japan, China, Vietnam, Cambodia, Taiwan, Malaysia, Singapore, Myanmar, Indonesia, Thailand, Laos, Philippines, Sri Lanka, India, Nepal, Papua New Guinea, and Australia. The Nephila pilipes can survive in many climate types, including temperate coastal, Mediterranean, subtropical and tropical savannah climates. They construct webs in bushes and trees, near surface water, and against buildings and other terrain structures. To reduce heat from the sun, like other spiders, Nephila spp. has a thermoregulatory behavior. Experiments show that when the temperature reaches 32 °C, Nephila spp. will adjust the angle between its body and the incoming sunlight, orienting its abdomen towards the sun but keeping the cephalothorax parallel to the web. When temperature further rises, it will align the full body along the sunlight direction, further reducing the area that is receiving heat from the sun. At temperature above 40 °C, Nephila spp. will abandon the web. Unlike other relatives, the distribution of N. pilipes doesn't depend on seasons. Adult females are active throughout four seasons and continuously lay eggs. Adult males are present in the population for longer times than females.

Now onto their webs. Generally, the web is not symmetric. Their silk appears to be yellow, hence the name golden orb-weavers. For adults, their webs are typically 0.5–1.0 m in diameter. However, when females aggregate together, their webs can be even larger. The hub of the web is usually at the top and prey will mostly be trapped on the lower web. The web has elastic silk at the center to absorb the kinetic energy of moving insects. Around the elastic part, some stiff structures fix the web to trees or other terrain structures. It has been reported that N. pilipes can adjust their silk composition, responding to different diet and environmental conditions. One study investigated the relationship between silk construction and prey types. When N. pilipes are fed with flies, small and airborne prey, the silk becomes more elastic, and the mesh size becomes smaller. When N. pilipes are fed crickets, large and powerful prey, the silk becomes stiff. Moreover, researchers also found that N. pilipes can change the silk's amino acid composition to fit their needs. The silk has excellent mechanical properties, more robust than most human-made materials, so the silk of Nephila spp. draws much attention in the field of material science. However, when silks are artificially spun in the lab, they often have inferior quality. Their webs, like other spiders, are subject to potential damage by birds and small mammals. When their webs are partially damaged, it usually takes N. pilipes 10–60 minutes to repair the web. However, if the damage is critical, the spider will consume the web and construct a new web in another nearby location.

Few studies have been conducted to investigate the enemies of N. pilipes. The primary enemy of N. pilipes in nature is the bird, which evolves to fly by and take them without being entangled by the web. It is rarely reported that N. pilipes are attacked and killed by parasites like Hymenoptera. To avoid predation by birds, female Nephila often construct an aggregated web system with other females or other orb-weavers, so their web system can shield them from birds. 

The bite of N. pilipes to humans is rarely reported. Its bites are likely similar to other orb-weaving spiders, which are reported to cause acute symptoms, including muscle pain, feeling of tightness, and reflexes exaggeration. Treatment with calcium gluconate can relieve victims from acute pains. Antiserum treatment can speed the victim's recovery.

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