Trichonephila clavipes | |
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Female, Jamaica | |
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Male, Jamaica | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Chelicerata |
Class: | Arachnida |
Order: | Araneae |
Infraorder: | Araneomorphae |
Family: | Nephilidae |
Genus: | Trichonephila |
Species: | T. clavipes |
Binomial name | |
Trichonephila clavipes | |
Synonyms | |
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Trichonephila clavipes (formerly known as Nephila clavipes), commonly known as the golden silk orb-weaver, golden silk spider, or colloquially banana spider (a name shared with several others), is an orb-weaving spider species which inhabits forests and wooded areas ranging from the southern US to Argentina. [3] It is indigenous to both continental North and South America. Known for the golden color of their silk, the large size of their females, and their distinctive red-brown and yellow coloring, T. clavipes construct large, asymmetrical circular webs attached to trees and low shrubs in woods to catch small- and medium-size flying prey, mostly insects. They are excellent web-builders, producing and utilizing seven different types of silk, [4] and they subdue their prey by injecting them with venom, as opposed to related species which immobilize their prey by wrapping them in silk first. They are not known to be aggressive towards humans, only biting out of self-defense if touched, and their relatively harmless venom has a low toxicity, posing little health concern to healthy human adults. Due to their prevalence in forests, T. clavipes may be encountered by hikers.
Like many orb-weaver species, T. clavipes shows sexual dimorphism, with females possessing both a larger size and more complex and noticeable coloration. Males of the species do not suffer sexual cannibalism or genital mutilation to the same rate that males of other related species in the subfamily Nephilinae do, making T. clavipes a focus of study into the mating behaviors of spiders. The species shows both monogynous and polygynous mating, with a preference for polygyny in most mating environments.
T. clavipes is a well-studied species with a high recognized value to humans because of their usefulness in spider silk research. Analysis of the species' genome, the first of the orb-weaving spiders to be completely annotated, has revealed 28 unique genes for the proteins comprising spider silk, known as spidroins. Furthermore, the silk of T. clavipes has the potential to aid in surgeries involving the nervous system, a capability which has been demonstrated in past experimental studies.
Like most orb-weavers, the species displays marked sexual dimorphism in both size and color pattern. T. clavipes females are some of the largest non-tarantula spiders in North America, ranging from 24 mm to 40 mm in length when fully developed. It is possible that they are even the largest orb-weaver species indigenous to the United States. Females also have very distinct coloring, making the species relatively easy to recognize. They have a silvery white cephalothorax and a longer orange-brown abdomen with two rows of small white-yellow spots. The abdomen changes color as the spider matures. Their legs consist of dark yellow and brown banding, and the first, second, and fourth leg pairs also contain black brush-like tufts of hair near the joints.
Males, meanwhile, are much smaller, about one-third to one-quarter the size of females at roughly 6 mm in length, and also have a more slender build. Their mass is roughly between 1/30th and 1/70th that of a large female. Male coloration, meanwhile, is much less complex, consisting of a dark brown body and legs. Males' legs contain a black band near the end of the tibial segment, in the same area as where the black hair tufts would be on a female.
T. clavipes resemble its congener Trichonephila plumipes in that the females both possess a collection of stiff hair on their legs. However, the hairs of T. plumipes are more closely set together than those of T. clavipes. [5]
The specific epithet clavipes is derived from the Latin: clava, which can mean "club" or "knotted staff"; and pes, meaning "of or pertaining to a foot". [6] As a whole, the name means "club-footed." Linnaeus, who named the species in 1767, was likely referring to the noticeable tufts of hair on the females' legs, giving them a clubbed or knotted appearance.
According to some scientists, Trichonephila clavipes belongs to the spider family Nephilidae, or golden orb-weaving spiders. [7] However, other researchers have done away with the Nephilidae family, instead assigning all golden orb-weaving spiders to the subfamily Nephilinae, within the family Araneidae. After the latest phylogenetic studies, the Nephilinae subfamily now contains the genera Nephila, to which T. clavipes originally belonged, and Trichonephila, its current assignment. Of all the Nephilinae genera, Trichonephila is the most species-rich genus. [7]
T. clavipes occurs most commonly in the Antilles and in Central America from Mexico in the north through Panama in the south. Less abundantly it occurs as far south as Argentina and in the north it occurs in parts of the southern states of the continental USA. Seasonally, it may range more widely; in the summer, it may be found as far north as lower Eastern Canada. Beyond 40° N latitude, these spiders seldom survive the winter.
T. clavipes may also be found within or near colonies of Metepeira incrassata , a Mexican colonial orb-weaver spider that typically forms large groups, ranging from a few hundreds to thousands of individual spiders. [8]
Because humans inadvertently transport spiders as passengers in cargo containers, plant nursery stock, and the like, T. clavipes generally occurs very unevenly over wide areas; often, patches of high local densities are found far from any other populations. Accidental human transport of the species increases markedly in late August to early September, when the spiders' reproduction is at its height.
In T. clavipes, males move from web to web, attempting to mate with the female web-owners. [9] Males risk death with each move to a new web, largely due to predation, and this mortality risk increases as the breeding season progresses, so that the risk is lower in the early stages of the season and highest in its later stages. As a result, males are more choosy in the early season than they are in the late season.
T. clavipes males may mate just once, monogynously, but are also capable of polygynous mating. [9] In many web-building spider species, including those of the Nephila genus, male spiders are only able to mate once due to behaviors such as sexual cannibalism and genital mutilation during copulation. These spiders thus display monogynous mating systems. Unusually, however, males of T. clavipes rarely face sexual cannibalism or genital mutilation, and are thus able to mate multiply. Monogyny can still occur for many male individuals, though, due to factors like ability to encounter female webs and ability to compete successfully with other males. Another, less conspicuous factor contributing to monogyny is that like many spider species, T. clavipes males produce a limited amount of sperm over their lifetimes. [10] Thus, sometimes a male will only have enough sperm for a single mating, forcing the male to invest in a monogynous relationship rather than searching for further mates.
There are several factors that play into a male's total mate number, but the ability of T. clavipes males to mate multiply allows males of all sizes to have equivalent mating success. It is thought that as a result, there is relaxed selection on male size in T. clavipes and other similar species. [9]
T. clavipes males have a limited amount of sperm available to them throughout their lifetimes and can therefore only inseminate a few females at most before they die. [10] Multiple mating success is dependent on the first female they choose to mate with: when males mate with virgin, newly molted females, they completely deplete their sperm supply, whereas when they mate with older, non-virgin females, they are able to retain some of their sperm for future matings. Additionally, males may still engage in mating behavior even when they do not have any sperm to give to the female, although the mating behavior is markedly less vigorous. [10] This inability of a male to inseminate further females may explain why male T. clavipes who have mated with virgin females will often remain on the female's web and guard her, rather than leave the web to search for future mates.
Mating with virgin females can be seen as a high-risk, high-reward situation for males of the species. [9] In situations where male T. clavipes are limited to monogyny in their environment, mating with virgin females offers the most reproductive payoff. Hence, a male using up his entire sperm reserves mating with a virgin makes sense; it allows the male to maximize his potential reproductive success with that single female. However, T. clavipes females do vary in mate quality, and virgin females happen to be the most active during a time period when a female's risk of mortality before she lays her fertilized eggs is highest. Thus, mating once with a virgin female and never mating again, although offering higher potential payoffs, also poses greater risks and a high variability in reproductive success. In fact, mating multiply with two or more non-virgin females is usually just as successful for males as mating monogynously with a virgin female, and given that the risks associated with non-virgin female mating are lower, it is likely that T. clavipes males prefer polygyny over monogyny. [9]
Mate guarding by T. clavipes males is size-dependent. [9] Because smaller males are less successful at physically competing with other males, they must invest much more time into successfully mating with a female on her web. As a result, it benefits the male more to search for a new web, rather than to spend even more time on the current web guarding the female with whom he has just mated. Conversely, larger males have a higher chance of winning access to a female at a new web and can thus afford to spend time engaging in mate guarding before searching for a new partner. The trade-off is that increased mate guarding generally results in a lower mate number, so males perceive a benefit in a higher mate number, guarding rates will generally decrease. [9]
Size is just one factor that influences male guarding behavior. Other factors like choice of a virgin female mate and sperm depletion can also make guarding behavior more likely, since the male cannot engage in further matings and no longer experiences a trade-off between guarding and mate searching. [10]
T. clavipes females construct large, vertical, asymmetric circular ("orb"-shaped) webs. The main web of a mature female can range from 1–2 meters in diameter, not counting the main filaments that anchor the web between trees; such anchor filaments may be 2–3 meters in length. A yellow pigment in the silk lends it a rich, golden glow in suitable lighting. As with many other orb-webs, it is common to see a trail of organic waste above the center which, as research has shown, attracts prey thanks to its rotten smell. [11] Given its size, the web is easily damaged by large flying bugs, birds, or debris; and needs to be repaired constantly. [12]
There are seven different types of silk glands across the orb-weaving spider species, each producing its own type of silk, and T. clavipes females possess all seven of these silk glands. [4] The glands are: (i) major ampullate, (ii) minor ampullate, (iii) piriform, (iv) aciniform, (v) tubuliform, (vi) flagelliform, and (vii) aggregate. The major ampullate silk shows high tensile strength and is thus used in structures that require stability, such as draglines, bridgelines, and the radii of webs. Minor ampullate silk is used as scaffolding during the web-building process, while piriform silk is used like cement, bonding fibers to each other and other structures. Aciniform silk is also strong, like major ampullate silk, but is flexible as well, allowing it to be used for wrapping prey and insulating egg cases. Tubuliform silk forms the tough outer shell of egg cases, and the flagelliform and aggregate silks are used in prey capture for their extensibility and stickiness. These silks differ in the specific spider fibroin, or "spidroin," proteins that comprise them. [4]
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). Research at Iowa State University has shown that T. clavipes silk, specifically in the draglines, has exceptionally high thermal conductivity, exceeding that of most metals. [13]
T. clavipes feed on small flying insects. Webs constructed by this species are used to catch this prey. They can feed on grasshoppers, flies, and other small insects. As the prey is entangled in the strong web, T. clavipes wrap it in silk like a casing. [14]
The spider is not aggressive and only bites if handled roughly; the venom is relatively harmless and rarely causes more than slight redness and temporary localized pain. [15]
T. clavipes has been incredibly useful in the study of spidroins; its spidroins were the first to be characterized, and its genome has been the first of the orb-weaving spiders to be annotated, contributing information about 28 unique spidroins. [4] In addition, T. clavipes had been chosen, because of its highly asymmetric web and elongated body shape, for an experiment in the ISS to test the effect of zero gravity on web-related behaviour. [16]
The silk of T. clavipes has recently been investigated to evaluate its usefulness in surgically improving mammalian neuronal regeneration. In vitro experiments showed that a filament of the silk can lead a severed neuron through the body to the site from which it was severed. The silk elicits no reaction from the immune system, and thereby escapes rejection by the host body. [17]
Spider silk is a protein fibre or silk spun by spiders. Spiders use silk to make webs or other structures that function as adhesive traps to catch prey, to entangle and restrain prey before biting, to transmit tactile information, or as nests or cocoons to protect their offspring. They can use the silk to suspend themselves from height, to float through the air, or to glide away from predators. Most spiders vary the thickness and adhesiveness of their silk according to its use.
Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name of the group. Araneids have eight similar eyes, hairy or spiny legs, and no stridulating organs.
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.
Trichonephila inaurata, synonym Nephila inaurata, commonly known as the red-legged golden orb-weaver spider or red-legged nephila, is a species of spider of the genus Trichonephila. It is native to southern and East Africa, as well as several islands of the western Indian Ocean.
Trichonephila clavata, also known as the Joro spider (ジョロウグモ , is a member of the Trichonephila genus. The spider can be found throughout Japan, Korea, Taiwan, China. Due to its large size and the bright, unique colors of the female Trichonephila, the spider is well-favored in Japan.
Zygiella x-notata, sometimes known as the missing sector orb weaver or the silver-sided sector spider, is a spider species in the family Araneidae. They are solitary spiders, residing in daily spun orb webs. Z. x-notata is a member of the genus Zygiella, the orb-weaving spiders. The adult female is easily recognized by the characteristic leaf-like mark on her posterior opisthosoma, caudal to the yellow-brown cephalothorax.
Trichonephila edulis is a species of large spider of the family Nephilidae, formerly placed in the genus Nephila. It is referred to by the common name Australian golden orb weaver. It is found in Indonesia from Java eastwards, Papua New Guinea, Australia, northern New Zealand, and New Caledonia.
Nephila pilipes 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, 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.
Larinioides sclopetarius, commonly called bridge-spider or gray cross-spider, is a relatively large orb-weaver spider with Holarctic distribution. These spiders originated in Europe, have been observed as south as the Mediterranean Coast and as north as Finland, and have been introduced to North America. They are often found on bridges, especially near light and over water. The species tends to live on steel objects and is seldom seen on vegetation. Females reach a body length of 10–14mm, and males 8–9mm. Their orb webs can have diameters of up to 70 cm.
Nephilengys is a genus of tropical spiders of the family Nephilidae, consisting of two currently described species. The genus Nephilingis has been split off from this genus. Both genera have been called hermit spiders from the habit staying in their retreats during the day; the name eunuch spiders has been used for Nephilengys alone. Males may sever parts of their palpal bulbs after copulation.
Sexual cannibalism is when an animal, usually the female, cannibalizes its mate prior to, during, or after copulation. It is a trait observed in many arachnid orders, several insect and crustacean clades, gastropods, and some snake species. Several hypotheses to explain this seemingly paradoxical behavior have been proposed. The adaptive foraging hypothesis, aggressive spillover hypothesis and mistaken identity hypothesis are among the proposed hypotheses to explain how sexual cannibalism evolved. This behavior is believed to have evolved as a manifestation of sexual conflict, occurring when the reproductive interests of males and females differ. In many species that exhibit sexual cannibalism, the female consumes the male upon detection. Females of cannibalistic species are generally hostile and unwilling to mate; thus many males of these species have developed adaptive behaviors to counteract female aggression.
Trichonephila plumipes, the Pacific golden orb weaver, is a species of spider found in Australia, Indonesia and some Pacific Islands, which exhibits extreme sexual dimorphism through its sexual cannibalism behavior. It is sometimes called the tiger spider due to its markings which look similar to a tiger. This species was formerly called Nephila plumipes. As with other spiders from the genus Nephila, these spiders have a distinct golden web.
Phonognatha graeffei, referred to as the leaf curling spider, is a common Australian spider found in woodlands and urban areas in the northeastern, eastern and southern states. A member of the family Araneidae, the orb-weavers, it was previously placed in Tetragnathidae.
Monogyny is a specialised mating system in which a male can only mate with one female throughout his lifetime, but the female may mate with more than one male. In this system, the males generally provide no paternal care. In many spider species that are monogynous, the males have two copulatory organs, which allows them to mate a maximum of twice throughout their lifetime. As is commonly seen in honeybees, ants and certain spider species, a male may put all his energy into a single copulation, knowing that this will lower his overall fitness. During copulation, monogynous males have adapted to cause self genital damage or even death to increase their chances of paternity.
Darwin's bark spider is an orb-weaver spider that produces the largest known orb webs, ranging from 900 to 28,000 square centimetres, with bridge lines spanning up to 25 metres (82 ft). The spider was discovered in Madagascar in the Andasibe-Mantadia National Park in 2009. Its silk is the toughest biological material ever studied. Its tensile strength is 1.6 GPa. The species was named in honour of the naturalist Charles Darwin on November 24, 2009—precisely 150 years after the publication of The Origin of Species.
Sexual selection in spiders shows how sexual selection explains the evolution of phenotypic traits in spiders. Male spiders have many complex courtship rituals and have to avoid being eaten by the females, with the males of most species surviving only a few matings and consequently having short life-spans.
Nephilidae is a spider family commonly referred to as golden orb-weavers. The various genera in Nephilidae were formerly placed in Tetragnathidae and Araneidae. All nephilid genera partially renew their webs.
Tetragnatha versicolor is a species of long-jawed orb weaver in the spider family Tetragnathidae. It is found throughout North America, Canada, Central America, and Cuba, but are most common in the United States. T. versicolor is heavily concentrated in New England and the west coast in states like California and Washington. T. versicolor is considered a habitat generalist, and can thrive in many different environments. While they can be found in places like Grasslands, Wetlands, Forests, etc., they prefer dryer areas like normal trees and shrubs. Unlike other spiders in the genus Tetragnatha, T. versicolor will rarely reside near aquatic environments. T. versicolor will typically be colored dark yellow or pale orange and average around 5 mm for males and 6.5 mm for females in length, which is very small for a spider. They are much longer than they are wide, making them very distinct. In addition, T. versicolor can be distinguished from other spiders in Tetragnatha by the distinct separation of the anterior/posterior eyes and the appearance of their reproductive organs. As an orb weaver spider, T. versicolor creates a web to hunt for prey. It will wait at night for prey to stumble into its web and use vibrational signals throughout the web to sense trapped prey. In terms of mating behavior, T. versicolor lacks a distinct courting ritual and will mate with any others in the proximity. Mating behavior is heavily affected by female mating history. In terms of interactions with humans, the bite of T. versicolor is venomous, but not known to cause significant harm.
Trichonephila is a genus of golden orb-weaver spiders that was first described by Friedrich Dahl in 1911, as a subgenus of Nephila. Trichonephila was elevated to the level of genus by Kuntner et al. in 2019. The genus Trichonephila belongs to the Nephilidae family.
Leucauge mariana is a long-jawed orb weaver spider, native to Central America and South America. Its web building and sexual behavior have been studied extensively. Males perform several kinds of courtship behavior to induce females to copulate and to use their sperm.