Oct 21

蜘蛛侠卷土重来 蜘蛛家族自相残杀

作者: 如果爱 iflove.com 自然传奇

蜘蛛侠拯救蜘蛛家族,蝎子蜈蚣自叹弗如。蜘蛛家族的丑闻传出,蜘蛛侠使出杀手锏。百万年来,蜘蛛已经进化成了高度复杂的食肉动物。凭借它飞丝走线的绝活,蜘蛛甚至连蝎子和蜈蚣都不放在眼里,更别说小飞虫了。有时,蜘蛛家族也会自相残杀,有些蜘蛛甚至会吃掉自己的配偶。蜘蛛侠卷土重来,蜘蛛家族自相残杀。如果爱 www.iflove.com温情献阅,蜘蛛侠与您相约,惊险不容错过!精彩尽在传奇saga节目,敬请关注,Coming soon.

中文解说词:蜘蛛侠卷土重来 蜘蛛家族自相残杀
English Title: Spider Man Returns: Home Defence
(字数:946字 撰稿:iflove.com专栏作家陈家伟,转载请注明出处)

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Keywords: Iflove TV, Man and Nature, Animals, Natures, Pleasure of Nature, Fabulous Nature, Animal, Saga Download, Documentary Download, Spider Man, Spider, carnivore, predator, Spider Game, Cobweb, StarScream, Ancient spider, King Spider

如果爱 www.iflove.com火爆推出,Saga传奇节目下载伴您每一天!即将为您推出的精彩美文是:《蜘蛛侠卷土重来 蜘蛛家族自相残杀》,自然妙趣不容错过!英文标题:Spider Man Returns with Hope。感动即将开始,敬请期待!Coming soon……

亲爱的宝贝,在上期如果爱www.iflove.com中,我们向大家介绍了八条腿的捕猎高手——蜘蛛。经过数百万年的进化,蜘蛛已经成了高度复杂的食肉动物;它们凭借高超的捕杀策略与挑战大范围居住环境的能力,成为生物界中的佼佼者。在今天的如果爱www.RuGuoAi.com中,我们继续为大家讲述蜘蛛侠的趣闻。

很少有人知道,淡水蜘蛛是水下杀手。一旦抓到猎物,淡水蜘蛛会马上用给猎物注射毒液。猎物被制服以后,淡水蜘蛛就将猎物拖到水下进食。对这种蜘蛛而言,鱼类无疑是最好的美味。

有时,蜘蛛家族也会自相残杀,有些蜘蛛甚至会吃掉自己的配偶。恐怖吧?

Spider Silk production

Silk production: An orb weaver producing silk from its spinneretsThe abdomen has no appendages except those that have been modified to form one to four (usually three) pairs of short, movable spinnerets, which emit silk. Each spinneret has many spigots, each of which is connected to one silk gland. There are at least six types of silk gland, each producing a different type of silk.[8] For more information about Spider or Spider Man, please visit www.iflove.com

Silk is mainly composed of a protein very similar to that used in insect silk. It is initially a liquid, and hardens not by exposure to air but as a result of being drawn out, which changes the internal structure of the protein.[22] It is similar in tensile strength to nylon and biological materials such as chitin, collagen and cellulose, but is much more elastic, in other words it can stretch much further before breaking or losing shape.[8]

Some spiders have a cribellum, a modified spinneret with up to 40,000 spigots, each of which produces a single very fine fiber. The fibers are pulled out by the calamistrum, a comb-like set of bristles on the jointed tip of the cribellum, and combined into a composite woolly thread that is very effective in snagging the bristles of insects. The earliest spiders had cribella, which produced the first silk capable of capturing insects, before spiders developed silk coated with sticky droplets. However most modern groups of spiders have lost the cribellum.[8]

Even species that do not build webs to catch prey use silk in several ways: as wrappers for sperm and for fertilized eggs; as a “safety rope”; for nest-building; and as “parachutes” by the young of some species.[8]

Spider Reproduction and life cycle

Further information: Spider cannibalism. The tiny male of the Golden orb weaver (Nephila clavipes) (near the top of the leaf) is saved by producing the right vibrations in the web, and may be too small to be worth eating.Spiders reproduce sexually and fertilization is internal but indirect, in other words the sperm is not inserted into the female’s body by the male’s genitals but by an intermediate stage. Unlike many land-living arthropods,[23] male spiders do not produce ready-made spermatophores (packages of sperm) but spin small sperm webs on to which they ejaculate and then transfer the sperm to syringe-like structures on the tips of their pedipalps. When a male detects signs of a female nearby he checks whether she is of the same species and whether she is ready to mate; for example in species that produce webs or “safety ropes”, the male can identify the species and sex of these objects by “smell”.[8] For more information about Spider or Spider Man, please visit www.iflove.com

Gasteracantha mammosa spiderlings next to their eggs capsule

wolf spider carrying its young in its egg sac.Spiders generally use elaborate courtship rituals to prevent the large females from eating the small males before fertilization, except where the male is so much smaller that he is not worth eating. In web-weaving species precise patterns of vibrations in the web are a major part of the rituals, while patterns of touches on the female’s body are important in many spiders that hunt actively, and may “hypnotize” the female. Gestures and dances by the male are important for jumping spiders, which have excellent eyesight. If courtship is successful, the male injects his sperm from the pedipalps into the female’s genital opening, known as the epigyne, on the underside of her abdomen. Female’s reproductive tracts vary from simple tubes to systems that include seminal receptacles in which females store sperm and release it when they are ready.[8]

Males of the genus Tidarren amputate one of their palps before maturation and enter adult life with one palp only. The palps are 20% of male’s body mass in this species, and detaching one of the two improves mobility. In the Yemeni species Tidarren argo, the remaining palp is then torn off by the female. The separated palp remains attached to the female’s epigynum for about four hours and apparently continues to function independently. In the meantime the female feeds on the palpless male.[24] In over 60% of cases the female of the Australian redback spider kills and eats the male after it inserts its second palp into the female’s genital opening; in fact the males co-operate by trying to impale themselves on the females’ fangs. Observation shows that most male redbacks never get an opportunity to mate, and the “lucky” ones increase the likely number of offspring by ensuring that the females are well-fed.[25] However males of most species survive a few matings, limited mainly by their short life spans. Some even live for a while in their mates’ webs.[26]

Females lay up to 3,000 eggs in one or more silk egg sacs,[8] which maintain a fairly constant humidity level.[26] In some species the females die afterwards, but females of other species protect the sacs by attaching them to their webs, hiding them in nests, carrying them in the chelicerae or attaching them to the spinnerets and dragging them along.[8]

Baby spiders pass all their larval stages inside the egg and hatch as spiderlings, very small and sexually immature but similar in shape to adults. Some spiders care for their young, for example a wolf spider’s brood cling to rough bristles on the mother’s back,[8] and females of some species respond to the “begging” behaviour of their young by giving them their prey, provided it is no longer struggling, or even regurgitate food.[26]

Like other arthropods, spiders have to molt to grow as their cuticle (“skin”) cannot stretch.[27] In some species males mate with newly-molted females, which are too weak to be dangerous to the males.[26] Most spiders live for only one to two years, although some tarantulas can live in captivity for over 20 years.[8][28]

Goliath birdeater (Theraphosa blondi), the largest spider, next to a ruler.

Spider Size

Spiders occur in a large range of sizes. The smallest, Patu Digua from Borneo, are less than 0.37 mm in body length. The largest and heaviest spiders occur among tarantulas, which can have body lengths up to 90 mm (about 3.5 inches) and leg spans up to 250 mm (about 10 inches).[29] For more information about Spider or Spider Man, please visit www.iflove.com

Spider Coloration

Only three classes of pigment (ommochromes, bilins and guanine) have been identified in spiders, although other pigments have been detected but not yet characterized. Melanins, carotenoids and pterins, very common in other animals, are apparently absent. In some species the exocuticle of the legs and prosoma is modified by a tanning process, resulting in brown coloration.[30] Bilins are found for example in Micrommata virescens, resulting in its green color. Guanine is responsible for the white markings of the European garden spider Araneus diadematus. It is in many species accumulated in specialized cells called guanocytes. In genera such as Tetragnatha, Leucauge, Argyrodes or Theridiosoma, guanine creates their silvery appearance. While guanine is originally an end-product of protein metabolism, its excretion can be blocked in spiders, leading to an increase in its storage.[30] Structural colors occur in some species, which are the result of the diffraction, scattering or interference of light, for example by modified setae or scales. The white prosoma of Argiope results from hairs reflecting the light, Lycosa and Josa both have areas of modified cuticle that act as light reflectors.[30]

Spider Ecology and behavior: Spider Non-predatory feeding

Spider Non-predatory feeding: Although spiders are generally regarded as predatory, the jumping spider Bagheera kiplingi gets over 90% of its food from fairly solid plant material produced by acacias as part of a mutually beneficial relationship with a species of ant.[31]

Juveniles of some spiders in the families Anyphaenidae, Corinnidae, Clubionidae, Thomisidae and Salticidae feed on plant nectar. Laboratory studies show that they do so deliberately and over extended periods, and periodically clean themselves while feeding. These spiders also prefer sugar solutions to plain water, which indicates that they are seeking nutrients. Since many spiders are nocturnal, the extent of nectar consumption by spiders may have been under-estimated. Nectar contains amino acids, lipids, vitamins and minerals in addition to sugars, and studies have shown that other spider species live longer when nectar is available. Feeding on nectar avoids the risks of struggles with prey, and the costs of producing venom and digestive enzymes.[32]

Various species are known to feed on dead arthropods (scavenging), web silk, and their own shed exoskeletons. Pollen caught in webs may also be eaten, and studies have shown that young spiders have a better chance of survival if they have the opportunity to eat pollen. In captivity, several spider species are also known to feed on bananas, marmalade, milk, egg yolk and sausages.[32] For more information about Spider or Spider Man, please visit www.iflove.com

Spider Methods of capturing prey

Main article: Spider web. This spider’s web serves both as a trap and as a way of making its home in a leaf.The best-known method of prey capture is by means of sticky webs. Varying placement of webs allows different species of spider to trap different insects in the same area, for example flat horizontal webs trap insects that fly up from vegetation underneath while flat vertical webs trap insects in horizontal flight. Web-building spiders have poor vision, but are extremely sensitive to vibrations.[8]

Females of the water spider Argyroneta aquatica build underwater “diving bell” webs which they fill with air and use for digesting prey, molting, mating and raising offspring. They live almost entirely within the bells, darting out to catch prey animals that touch the bell or the threads that anchor it. [33] A few spiders use the surfaces of lakes and ponds as “webs”, detecting trapped insects by the vibrations that these cause while struggling.[8]

Net-casting spiders weave only small webs but then manipulate them to trap prey. Those of the genus Hyptiotes and the family Theridiosomatidae stretch their webs and then release them when prey strike them, but do not actively move their webs. Those of the family Deinopidae weave even smaller webs, hold them outstretched between their first two pairs of legs, and lunge and push the webs as much as twice their own body length to trap prey, and this move may increase the webs’ area by a factor of up to ten. Experiments have shown that Deinopis spinosus has two different techniques for trapping prey: backwards strikes to catch flying insects, whose vibrations it detects; and forward strikes to catch ground-walking prey that it sees. These two techniques have also been observed in other deinopids. Walking insects form most of the prey of most deinopids, but one population of Deinopis subrufus appears to live mainly on tipulid flies that they catch with the backwards strike.[34]

Mature female bolas spiders of the genus Mastophora build “webs” that consist of only a single “trapeze line”, which they patrol. They also construct a bolas made of a single thread, tipped with a large ball of very wet sticky silk. They emit chemicals that resemble the pheromones of moths, and then swing the bolas at the moths. Although they miss on about 50% of strikes, they catch about the same weight of insects per night as web-weaving spiders of similar size. The spiders eat the bolas if they have not made a kill in about 30 minutes, rest for a while, and then make new bolas.[35][36] Juveniles and adult males are much smaller and do not make bolas. Instead they release different pheromones that attract moth flies, and catch them with their front pairs of legs.[37] For more information about Spider or Spider Man, please visit www.iflove.com

Trapdoor spider (family: Ctenizidae), an ambush predator.The primitive Liphistiidae, the “trapdoor spiders” (family Ctenizidae) and many tarantulas are ambush predators that lurk in burrows, often closed by trapdoors and often surrounded by networks of silk threads that alert these spiders to the presence of prey.[13] Other ambush predators do without such aids, including many crab spiders,[8] and a few species that prey on bees, which see ultraviolet, can adjust their ultraviolet reflectance to match the flowers in which they are lurking.[30] Wolf spiders, jumping spiders, fishing spiders and some crab spiders capture prey by chasing it, and rely mainly on vision to locate prey.[8]

Portia uses both webs and cunning, versatile tactics to overcome prey.[38]Some jumping spiders of the genus Portia hunt other spiders in ways that seem intelligent,[18] outflanking their victims or luring them from their webs. Laboratory studies show that Portia’s instinctive tactics are only starting points for a trial-and-error approach from which these spiders learn very quickly how to overcome new prey species.[38] However they seem to be relatively slow “thinkers”, which is not surprising, as their brains are vastly smaller than those of mammalian predators.[18]

An ant-mimicking jumping spiderAnt-mimicking spiders face several challenges: they generally develop slimmer abdomens and false “waists” in the cephalothorax to mimic the three distinct regions (tagmata) of an ant’s body; they wave the first pair of legs in form to their heads to mimic antennae, which spiders lack, and to conceal the fact that they have eight legs rather than six; they develop large color patches round one pair of eyes to disguise the fact that they generally have eight simple eyes, while ants have two compound eyes; they cover their bodies with reflective hairs to resemble the shiny bodies of ants. In some spider species, males and females mimic different ant species, as female spiders are usually much larger than males. Ant-mimicking spiders also modify their behavior to resemble that of the target species of ant; for example, many adopt a zig-zag pattern of movement, ant-mimicking jumping spiders avoid jumping, and spiders of the genus Synemosyna walk on the outer edges of leaves in the same way as Pseudomyrmex. Ant-mimicry in many spiders and other arthropods may be for protection from predators that hunt by sight, including birds, lizards and spiders. However, several ant-mimicking spiders prey either on ants or on the ants’ “livestock,” such as aphids. When at rest, the ant-mimicking crab spider Amyciaea does not closely resemble Oecophylla, but while hunting it imitates the behavior of a dying ant to attract worker ants. After a kill, some ant-mimicking spiders hold their victims between themselves and large groups of ants to avoid being attacked.[39]

Spider Defense

Threat display by a Sydney funnel-web spider (Atrax robustus).There is strong evidence that spiders’ coloration is camouflage that helps them to evade their major predators, birds and parasitic wasps, both of which have good color vision. Many spider species are colored so as to merge with their most common backgrounds, and some have disruptive coloration, stripes and blotches that break up their outlines. In a few species, such as the Hawaiian happy-face spider, Theridion grallator, several coloration schemes are present in a ratio that appears to remain constant, and this may make it more difficult for predators to recognize the species. Most spiders are insufficiently dangerous or unpleasant-tasting for warning coloration to offer much benefit. However a few species with powerful venoms, large jaws or irritant hairs have patches of warning colors, and some actively display these colors when threatened.[30] For more information about Spider or Spider Man, please visit www.iflove.com

Many of the family Theraphosidae, which includes tarantulas and baboon spiders, have urticating hairs on their abdomens and use their legs to flick them at attackers. These hairs are fine setae (bristles) with fragile bases and a row of barbs on the tip. The barbs cause intense irritation but there is no evidence that they carry any kind of venom.[41] A few defend themselves against wasps by including networks of very robust threads in their webs, giving the spider time to flee while the wasps are struggling with the obstacles.[42] The golden wheeling spider Carparachne aureoflava of the Namibian desert escapes parasitic wasps by flipping onto its side and cartwheeling down sand dunes.[43]

Spider Social spiders

Main article: Social spider. A few species of spiders that build webs live together in large colonies and show social behavior, although not as complex as in social insects. Anelosimus eximius (in the family Theridiidae) can form colonies of up to 50,000 individuals.[44] The genus Anelosimus has a strong tendency towards sociality: all known American species are social, and species in Madagascar are at least somewhat social.[45] Members of other species in the same family but several different genera have independently developed social behavior. For example, although Theridion nigroannulatum belongs to a genus with no other social species, T. nigroannulatum build colonies that may contain several thousand individuals that co-operate in prey capture and share food.[46] Other communal spiders include several Philoponella species (family Uloboridae), Agelena consociata (family Agelenidae) and Mallos gregalis (family Dictynidae).[47] Social predatory spiders need to defend their prey against kleptoparasites (“thieves”), and larger colonies are more successful in this.[48] The herbivorous spider Bagheera kiplingi lives in small colonies which help to protect eggs and spiderlings.[31] Even widow spiders (genus Latrodectus), which are notoriously aggressive and cannibalistic, have formed small colonies in captivity, sharing webs and feeding together.[49]

Web types: Spider Web

Main article: Spider web. There is no consistent relationship between the classification of spiders and the types of web they build: species in the same genera may build very similar or significantly different webs. Nor is there much correspondence between spiders’ classification and the chemical composition of their silks. Convergent evolution in web construction, in other words use of similar techniques by remotely-related species, is “rampant”. Non-orb web designs and the spinning behaviors that produce them have received very little attention from arachnologists, despite the fact that the majority of spiders build non-orb webs. The basic radial-then-spiral sequence visible in orb webs and the “sense of direction” required to build them may have been inherited from the common ancestors of most spider groups.[50] It used to be thought that the sticky orb web was an evolutionary innovation resulting in the diversification of the Orbiculariae. Now, however, it appears that non-orb spiders are a sub-group that evolved from orb-web spiders, and non-orb spiders have over 40% more species and are four times as abundant as orb-web spiders. Their greater success may be due to the fact that sphecid wasps, which are often the dominant predators on spiders, much prefer to attack spiders that have flat webs.[51]

Spider Orb webs

Nephila clavata, a golden orb weaverAbout half the potential prey that hit orb webs escape. A web has to perform three functions: intercepting the prey (intersection); absorbing its momentum without breaking (stopping); and trapping the prey by entangling it or sticking to it (retention). No single design is best for all prey. For example: wider spacing of lines will increase the web’s area and hence its ability to intercept prey, but reduce its stopping power and retention; closer spacing, larger sticky droplets and thicker lines would improve retention, but would make it easier for potential prey to see and avoid the web, at least during the day. However there are no consistent differences between orb webs built for use during the day and those built for use at night. In fact there is no simple relationship between orb web design features and the prey they capture, as each orb-weaving species takes a wide range of prey.[50]

The hubs of orb webs, where the spiders lurk, are usually above the center as the spiders can move downwards faster than upwards. If there is an obvious direction in which the spider can retreat to avoid its own predators, the hub is usually offset towards that direction.[50]

Horizontal orb webs are fairly common, despite being less effective at intercepting and retaining prey and more vulnerable to damage by rain and falling debris. Various researchers have suggested that horizontal webs offer compensating advantages, such as: reduced vulnerability to wind damage; reduced visibility to prey flying upwards, because of the back-lighting from the sky; enabling oscillations to catch insects in slow horizontal flight. However there is no single explanation for the common use of horizontal orb webs.[50]

Spiders often attach highly visible silk bands called decorations or stabilimenta to their webs. Field research suggests that webs with more decorative bands captured more prey per hour.[52] However a laboratory study showed that spiders reduce the building of these decorations if they sense the presence of predators.[53]

There are several unusual variants of orb web, many of them convergently evolved, including: attachment of lines to the surface of water, possibly to trap insects in or on the surface; webs with twigs through their centers, possibly to hide the spiders from predators; “ladder-like” webs that appear most effective in catching moths. However the significance of many variations is unclear.[50] For more information about Spider or Spider Man, please visit www.iflove.com

In 1973, Skylab 3 took two orb-web spiders into space to test their web-spinning capabilities in zero gravity. At first both produced rather sloppy webs, but they adapted quickly.[54]

Tangleweb / cobweb spiders

A funnel web.Members of the family Theridiidae weave irregular, tangled, three-dimensional webs, popularly known as cobwebs.There seems to be an evolutionary trend towards a reduction in the amount of sticky silk used, leading to its total absence in some species. The construction of cobwebs is less sterotyped than that of orb-webs, and may take several days.[51]

Spider Other types of webs

The Linyphiidae generally make horizontal but uneven sheets, with tangles of stopping threads above. Insects that hit the stopping threads fall on to the sheet or are shaken on to it by the spider, and are held by sticky threads on the sheet until the spider can attack from below.[55]

Spider Evolution

Main article: Spider evolution. Shultz (2007)’s evolutionary family tree of arachnids[56] – † marks extinct groups.

Spider preserved in amberThe fossil record of spiders is very poor[57]. Spider fossils are rare because spiders’ bodies are very soft. The oldest known amber that contains fossil arthropods dates from 130 million years ago in the Early Cretaceous period. In addition to preserving spiders’ anatomy in very fine detail, pieces of amber show spiders mating, killing prey, producing silk and possibly caring for their young. In a few cases amber has preserved spiders’ egg sacs and webs, occasionally with prey attached;[58] the oldest fossil web found so far is 100 million years old.[59] Earlier spider fossils come from a few lagerstätten, places where conditions were exceptionally suited to preserving fairly soft tissues.[58]

Palaeotarbus jerami, a trigonotarbid and the oldest known arachnidThe oldest known arachnid is the trigonotarbid Palaeotarbus jerami, from about 420 million years ago in the Silurian period, and had a triangular cephalothorax and segmented abdomen, as well as eight legs and a pair of pedipalps.[60] Attercopus fimbriunguis, from 386 million years ago in the Devonian period, bears the earliest known silk-producing spigots, and was therefore hailed as a spider.[61] However these spigots may have been mounted on the underside of the abdomen rather than on spinnerets, which are modified appendages and whose mobility is important in the building of webs. Hence Attercopus and the similar Permian archnid Permarachne may not have been true spiders, and probably used silk for lining nests or producing egg-cases rather than for building webs.[62]

Several Carboniferous spiders were members of the Mesothelae, a primitive group now represented only by the Liphistiidae.[61] The mesothelid Paleothele montceauensis, from the Late Carboniferous over 299 million years ago, had five spinnerets.[63] Although the Permian period 299 to 251 million years ago saw rapid diversification of flying insects, there are very few fossil spiders from this period.[61]

The main groups of modern spiders, Mygalomorphae and Araneomorphae, first appear in the Triassic well before 200 million years ago. Some Triassic mygalomorphs appear to be members of the family Hexathelidae, whose modern members include the notorious Sydney funnel-web spider, and their spinnerets appear adapted for building funnel-shaped webs to catch jumping insects. Araneomorphae account for the great majority of modern spiders, including those that weave the familiar orb-shaped webs. The Jurassic and Cretaceous periods provide a large number of fossil spiders, including representatives of many modern families.[61]

Spider Family tree

It is now agreed that spiders (Araneae) are monophyletic, in other words members of a group that contains a common ancestor plus all and only its descendants.[64] There has been debate about what are their closest evolutionary relatives and how all of these evolved from the ancestral chelicerates, which were marine animals. The cladogram on the right is based on J.W. Shultz’ analysis (2007). Other views include proposals that: scorpions are more closely related to the extinct marine scorpion-like eurypterids than to spiders; spiders and Amblypygi are a monopyhletic group. The appearance of several multi-way branchings in the tree on the right shows that there are still uncertainties about relationships between the groups involved.[64]

Arachnids lack some features of other chelicerates, including backward-pointing mouths and gnathobases (“jaw bases”) at the bases of their legs;[64] both of these features are part of the ancestral arthropod feeding system.[65] Instead they have mouths that point forwards and downwards, and all have some means of breathing air.[64] Spiders (Araneae) are distinguished from other arachnid groups by several characteristics, including spinnerets and, in males, pedipalps that are specially adapted for sperm transfer.[66]

Spider Taxonomy

Spider taxonomy and List of families of spiders
Spiders are divided into two sub-orders, Mesothelae and Opisthothelae, of which the latter contains two infra-orders, Mygalomorphae and Araneomorphae. Over 40,000 living species of spiders (order Araneae) have been identified and are currently grouped into about 110 families and about 3,700 genera by arachnologists.[2][66]

Spider diversity Features

Sub-order Species Genera Families Segmented plates on top of abdomen[67] Ganglia in abdomen Spinnerets[67] Striking direction of fangs[8] Mesothelae 87 5 1 Yes Yes Four pairs, in some species one pair fused, under middle of abdomen Downwards and forwards Mygalomorphae 2,600 300 15 No, but yes in some fossils No One, two or three pairs under rear of abdomen Araneomorphae 37,000 3,400 93 From sides to center, like pincers For more information about Spider or Spider Man, please visit www.iflove.com

Spider Mesothelae

Ryuthela secundaria, a member of the Liphistiidae[68]Main article: Mesothelae. The only living members of the primitive Mesothelae are the family Liphistiidae, found only in Southeast Asia, China, and Japan.[66] Most of the Liphistiidae construct silk-lined burrows with thin trapdoors, although some species of the genus Liphistius build camouflaged silk tubes with a second trapdoor as an emergency exit. Members of the genus Liphistius run silk “tripwires” outwards from their tunnels to help them detect approaching prey, while those of genus Heptathela do not and instead rely on their built-in vibration sensors.[69] Spiders of the genus Heptathela have no venom glands although they do have venom gland outlets on the the fang tip.[70]

The extinct families Arthrolycosidae, found in Carboniferous and Permian rocks, and Arthromygalidae, so far found only in Carboniferous rocks, have been classified as members of the Mesothelae.[71]

Spider Mygalomorphae

A Mexican red-kneed tarantula Brachypelma smithiMain article: Mygalomorphae. The Mygalomorphae, which first appeared in the Triassic period,[61] are generally heavily-built and hairy, with large, robust chelicerae and fangs.[66] Well-known examples include tarantulas, trapdoor spiders and the Australasian funnel-web spiders.[8] Most spend the majority of their time in burrows, and some run silk tripwires out from these, but a few build webs to capture prey. However mygalomorphs cannot produce the pirifom silk that the Araneomorphae use as instant adhesive to glue silk to surfaces or to other strands of silk, and this makes web construction more difficult for mygalomorphs. Since mygalomorphs rarely “balloon” by using air currents for transport, their populations often form clumps.[66] In addition to arthropods, mygalomorphs prey on frogs and lizards, and snails.[72]

Spider Araneomorphae

The pincer-like fangs of an Cheiracanthium punctoriumMain article: Araneomorphae. In addition to accounting for over 90% of spider species, the Araneomorphae have the most diverse lifestyles as they include orb-web spiders, the cursorial wolf spiders, and jumping spiders, [66] as well as the only known herbivorous spider, Bagheera kiplingi.[31]

Spider bites

Main article: Spider bite. Symptoms that are most common in all types of toxic spider bites.[73]Most spiders will only bite humans in self-defense, and few produce worse effects than a mosquito bite or bee-sting.[74] Most of those with medically serious bites, such as recluse spiders and widow spiders, are shy and bite only when they feel threatened, although this can easily arise by accident.[75][76] Funnel web spiders’ defensive tactics are aggressive and their venom, although they rarely inject much, has resulted in 13 known human deaths.[77] On the other hand the Brazilian wandering spider requires very little provocation.[78]

There were about 100 reliably reported deaths from spider bites in the 20th century,[79] but about 1,500 from jellyfish stings.[80] Many alleged cases of spider bites may represent incorrect diagnoses,[81] which would make it more difficult to check the effectiveness of treatments for genuine bites.[82] For more information about Spider or Spider Man, please visit www.iflove.com

Spider Benefits to humans

Cooked tarantula spiders are considered a delicacy in Cambodia.Cooked tarantula spiders are considered a delicacy in Cambodia,[83] and by the Piaroa Indians of southern Venezuela – provided the highly irritant hairs, the spiders’ main defense system, are removed first.[84]

Spider venoms may be a less polluting alternative to conventional pesticides as they are deadly to insects but the great majority are harmless to vertebrates. Australian funnel web spiders are a promising source as most of the world’s insect pests have had no opportunity to develop any immunity to their venom, and funnel web spiders thrive in captivity and are easy to “milk”. It may be possible to target specific pests by engineering genes for the production of spider toxins into viruses that infect species such as cotton bollworms.[85]

Possible medical uses for spider venoms are being investigated, for the treatment of cardiac arrhythmia,[86] Alzheimer’s disease,[87] strokes,[88] and erectile dysfunction.[89]

Because spider silk is both light and very strong, attempts are being made to produce it in goats’ milk and in the leaves of plants, by means of genetic engineering.[90] [91]

Spider Arachnophobia

Arachnophobia Story. Arachnophobia is a specific phobia, an abnormal fear of spiders or anything reminiscent of spiders, such as webs or spider-like shapes. It is one of the most common specific phobias,[92][93] and some statistics show that 50 percent of women and 10 percent of men show symptoms.[94]

It may be an exaggerated form of an instinctive response that helped early humans to survive,[95] or perhaps a cultural phenomenon that is most common in predominantly European societies.[96] For more information about Spider or Spider Man, please visit www.iflove.com

Spiders in symbolism and culture

Cultural depictions of spiders. This Moche ceramic depicts a spider, and dates from around 300 CE.Spiders have been the focus of fears, stories and mythologies of various cultures for centuries.[97] They have symbolized patience due to their hunting technique of setting webs and waiting for prey, as well as mischief and malice for the painful death their venom causes.[98]

Web-spinning also caused the association of the spider with creation myths as they seem to have the ability to produce their own worlds.[99] The Moche people of ancient Peru worshipped nature.[100] They placed emphasis on animals and often depicted spiders in their art.[101]

蜘蛛的杀手锏:很少有人知道,淡水蜘蛛是水下杀手。一旦抓到猎物,淡水蜘蛛会马上用给猎物注射毒液。猎物被制服以后,淡水蜘蛛就将猎物拖到水下进食。对这种蜘蛛而言,鱼类无疑是最好的美味。

蜘蛛家族的丑闻:有时,蜘蛛家族也会自相残杀,有些蜘蛛甚至会吃掉自己的配偶。现在就让我们打开如果爱www.iflove.com,一睹这些捕猎高手的风采吧!

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