See also: Spider (homonymy)
The spiders or aranéides (of the Araneae ) are Prédateur S Invertébré S Arthropode S of Arachnide S. They are not insects. They are included in a vaster group also containing the scorpion S, Uropyge S, Acarien S, Tique S, and Opilion S.
They have all eight legs, neither wings neither antennas, nor parts masticatrices in the mouth. They have simple and multiple eyes, and produce silk (a protein synthesized by a gland generally located at the end of the abdomen). This silk is used to produce the wire which enables them to move vertically or laterally when there is wind, to weave their fabric, or cocoons imprisoning their preys or protecting their eggs or small, to even make a provisional reserve of sperm or a dome enabling them to store air under water (soft).
Many species drive out freely and without making fabrics, while moving, or with the mounting, sometimes in a hole which can be built like a trap.
As predatory, the spiders play an important role in the regulation of the populations of insects, and they themselves are controlled by predatory the often specific ones (reptiles, birds or insects of the family of the Pompilidae). They adapted to almost all the mediums, cavernicoles with mountainous, of the Arctic mediums to equatorial. Only the very cold salt water and very high-altitudes and mediums were not colonized by the araneae.
the scientific study of the spiders names the Aranéologie (or Arachnologie).
La irrational fear of the spiders names the Arachnophobie, one of the most common phobias.
Except those pertaining to two families (Uloboridae and Holarchaeidae), and to the group of the Mesothelae (350 species in all), all the spiders can inoculate a Venin to protect and/or kill and liquefy the internal bodies their preys.
Many bites of great species are very painful, but will not leave after-effects. Only 200 known species have punctures which can present health issues with the man.
FoodAll the known species of spiders are predatory, without exception. They exclusively nourish alive preys which they drive out either using traps, or with the mounting.
Like all Arachnida, the spider absorbs only liquids: it must thus liquefy its preys before being able to nourish itself some.
SilkThe silk-producing glands produce silk spun by small articulated protuberances (the Filière S), generally 6, located on the ventral face more or less at the end of the abdomen. Silk is liquid in glands, but is solidified in Fibrille S once left by the Fusule S, under the effect of the traction exerted by the legs of the animal. The silk wire is in fact consisted an interlacing of a high number of elementary fibrillae, of 0,05 µm diameter each one. The diameter of the silk wire varies between 25 and 70 µm (with equivalent diameter, these wire are harder than of steel and have a memory of form 5 to 12 times larger than the Latex). The spiders produce several types of silks according to the use which they will make. Sticking silk is only one of the types existing.
Principal uses of silk:
- packing of the eggs (Cocon)
- tapissage of the burrow of the species which live under ground
- clothes industry of hunting weapons (Bolas of the Mastophora, nets of the Dinopis)
- subaqueous manufacture of shelter (diving bell of the Argyronète S)
- wire of safety during a jump or a voluntary fall to flee
- wire of displacement (wire of ARIANE)
- average of dispersion air of the young people (gossamer threads, Ballooning)
- emmaillotage of the captured preys
- weaving of the fabrics of moults (mattress)
- weaving of the spermatic fabrics
- weaving of the fabrics of trapping of the preys
It is considered that the initial use of silk was the manufacture of the cocoon to protect eggs because the spiders considered as primitives do not weave a fabric.
See also: Cobweb
The VenomThe majority of the species of spiders have poison glands. Very few species present a real danger to the human beings. Either because the spiders are well too small to be able to bore the human skin, or because they do not have an aggressive behavior. It also should be noted that species belonging to the Mygalomorphe S have, on the abdomen, of the irritant hairs. Among the dangerous species, let us quote the black Veuve ( Latrodectus mactans ) present in the hot areas, the Atrax robustus present in Australia and New Zealand, etc
The spiders have two Chélicère S in front of the body and which frames the mouth: these are the appendices which inject venom. They consist of a large Stipe and a mobile hook to the end of which the Canal with venom emerges. These chélicères can be also used to transport preys, to dilacerate them, transport the ovigerous cocoon, etc
MorphologyWith the difference of the Insect S, the spiders are made of two parts: the Céphalothorax or prosome (fusion enters the head and the Thorax) and the Abdomen. The abdomen carries the dies or bodies which produce the Soie, and, except at some primitive Taxon S, did not retain the external segmentations. At the end of the céphalothorax are the Pédipalpe S, sensors for the examination of the preys and their handling. In the male adults, the end of the pédipalpe carries also the bulb copulator.
The two parts are connected by an end Pédoncule, which is the last Somite (segment) of the céphalothorax. This celebrity was lost in other Arachnida, not being present, for example, that with the state Embryon naire at the scorpion S.
The céphalothorax carries on its ventral face four pairs of articulated legs laid out around the Sternum. Each leg is composed of 7 articles: base towards the apex respectively, one observes a hip (Coxa), a court Trochanter, a length Fémur, shorter Patelle, a length tibia, a métatarse and a tarsus. This last finishes into 2 or 3 claws, which intervene in the handling of silk and displacement on the fabric. Are associated with the legs various structures related to the particular lifestyle of each taxon, that they are combs for " carder" silk, of the spine S, Crin S, Poil S which are used as sensors, of the structures of stridulation.
VisionThe simple eyes, placed in front of the céphalothorax, are often 8, but strongly vary according to tax (some do not have eyes). The ocular provision, often a distinctive feature, is specific to the taxon. Sometimes a pair of eyes is developed than the others, which then detect only vibrations around the spider. The vision is generally bad, although certain species actively chasseuses developed a very good vision.
Breathing apparatuses and circulatoryThe spiders have a circulatory Système open. Their body is filled with Hémolymphe, which is pumped by the heart with the bodies. The spiders breathe either by lungs in layers, or by a system Trachée N, or, at some small species, directly through the skin.
Life cycle and reproduction
- the seasonal spiders live from 6 to 8 months and die after having laid their eggs.
- the annual spiders live from 1 to 2 years and die after the blossoming of the young people.
- the perennial spiders live several years (mygale S, Filistate S)
Like all the Arthropode S the growth is done by successive moults of the Exosquelette. According to the species, there is from 8 to 13 moults to reach the adult state. The mygales continue to moult about once per annum after the adulthood.
The sexual Dimorphisme of the spiders is generally weak, the females are characterized by a higher size, a larger abdomen. The adult males recognize themselves in addition to their small size to their pédipalpes which carry at their end a body of storage of sperm called bulb copulatoire. The difference in size is sometimes spectacular, as at the Néphiles where it is difficult to believe that it is about the same species.
The spiders are Ovipare S, they lay eggs, which are packed in a silk cocoon. According to the size of the species the number of eggs varies from one to several thousands. So certain species give up the cocoon, others transport it hung to the Filière S or maintained by the chélicères. To these last species, as of their blossoming, the young people go up on the back of their mother who protects them and nourishes them until they are able to be defended.
Many species have a bridal parade elaborate especially consisting in for the male being made distinguish from a prey to avoid being devoured. The bridal cannibalism of the black Widowed (Latrodectus mactans) or of the épeire (Araneus diadematus) is not very widespread.
The male weaves a spermatic fabric where it deposits its sperm which it then aspires in its bulbs copulatoires.
Place des spiders in the animal kingdomhere is a site not badly:
Taxonomy and diversityThe order of Araneae is subdivided in two sub-orders: the sub-order of the Opisthothelae, which is consisted of the Infra-order S of the Mygalomorphae (mygales) and of the Araneomorphae (modern species); and the sub-order of the Mesothelae, whose members are primitive species of the Asia.
The 40.000 species of spiders are varied: larger, the Theraphosa leblondi , which can measure until more than 30 cm, until tiny the Patu marplesi , not larger than a pinhead (0,5 mm), while passing by well-known the Araneus diadematus , the épeire diadem.
Types of spidersSome important families and regroupings:
- Atypidae (Mygales): they have blades jawbones and live in a burrow prolonged by a silk tube; they are more frequent on a calcareous ground .
Ctenizidae (Mygales): they do not have blades jawbones and live in a burrow closed by a Opercule.
Cribellatae : regrouping of a disparate whole of tisseuses spiders of fabrics; extremely fine silk has a characteristic bluish appearance.
Eresidae : live a silk tube inserted in the ground and finished by a hood; large massive, black, discrete spiders; are in the moors.
Amaurobiidae : large spiders cribellates weaving an irregular fabric; they manufacture a tubular retirement, against the walls or under the stones.
Dictynidae : small spiders cribellates (max: 5mm) building very irregular fabrics especially in the low vegetation but also on the walls; the abdomen is often very characteristic.
Oecobiidae : small spiders with an almost circular céphalothorax and a large anal tuber; the nest has a spangled form.
- Uloboridae : spiders cribellates with the fabrics geometrical complete ( Uluborus ) or segmented ( Hyptiotes ), horizontal or not very tilted; no poison glands.
Oonopidae : wandering spiders night, of pink color, very small, with six eyes; one finds them in the houses or the refuses.
Dysderidae : grosses or average spiders wandering with six eyes, strongly armed; night manners, shelter under the stones or the deadwood during the day.
Segestriidae : lengthened spiders which make tubular fabrics in holes in the cracks of the walls or the rocks, with wire warning signals radians prolonging the tube; legs III are held parallel to I and II.
Scytodidae : spider-spitting which projects with one or two centimetres of distance a small gum ball which limes their prey; have three groups of two eyes and a céphalothorax very curvature.
Pholcidae : spiders provided with very long legs; they make very irregular fabrics in the shape of tablecloth and balance them when they are disturbed; like themselves in the dwellings.
Zodariidae : small spiders which nourish ants; the legs do not have spines, the color is purplished; are primarily in the wood of pines.
Gnaphosidae or Drassidae: night spiders living under the stones in silk cabins; the former dies are long and quite visible, the posterior median eyes are brought closer; many kinds.
Liocranidae : night spiders which are distinguished from Clubionidae by two lines of spines on the forefeet; they live the low vegetation; at the time of the parade, the male makes vibrate its two pairs of forefeet at high speed in front of the female; the cocoon is installed in cabins covered with ground.
Zoridae : spiders having of the black eyes, posterior largest than the others; the céphalothorax is frayed forwards, the forefeet are provided with two lines of spines; the females keep their cocoons under the stones or the sheets fallen on the ground.
Anyphaenidae : similar to Clubionidae; only one species with a yellow band and two rafters black on the abdomen; arboricolous life, drive out with the mounting.
Sparassidae : the legs are very spread out; the most remarkable species is Micrommata virescens, of green color, which meets in the low vegetation of moist environments.
Thomisidae : they are the Spider-crabs, very often mimetic support where they drive out with mounting (flowers, ground, etc); legs I and II are much longer and stronger than III and IV; their venom acts very quickly.
Philodromidae : spiders with the body rather flattened, with almost equal legs; they drive out with the mounting in the vegetation and can move very quickly.
Salticidae : jumping diurnal spiders with legs in general short and strong, the former ones sometimes reinflated; the four large former eyes are sometimes mobile; they do not hesitate to jump over the finger which approaches. It is the family which contains the greatest number of species in the world.
Oxyopidae : the legs all are long and thorny; they drive out with courre like the lycoses or while jumping like the salticides.
Lycosidae : the spider-wolves drive out while running and while leaping on their preys; small former eyes on a line, two very large posterior eyes; they transport their eggs in a cocoon fixed on the dies or their young people on the back. Example: the kinds Acantholycosa , Alopecosa , Arctosa , Aulonia , Hygrolycosa , Pirated , Tricca , Trochosa and Xerolycosa .
- Pardosa .
Le network of wire of the cobweb is at the origin of the use of the English word Net , to create the word “Internet” symbolizing the complex system of interconnection of this network.
the spider with the cinema
It is present, with Spider-Man, or Arachne, one of the monsters which must fight the hero of the trilogy of the Seigneur of the Rings , or in many horror films. One of the films which exploits best its potential horrifiquement phobic is Arachnophobia of Frank Marshall, with Jeff Daniels, in 1990. Much older and improbable, the famous Tarantula (1955) puts in scene a giant spider which frightens the populations the made-to-order of Godzilla. The film with the characteristic to encrust a true tarantula increased by optical effect, which gives an effect of a realism seizing for the time. Lastly, the film of author also leant in a metaphorical way on the strangeness of the animal thanks to Spider of David Cronenberg, in 2002.
the man constitutes a threat for certain species of spiders
Sought by collectors, various tropical species make the object of a trade and a traffic (dead or sharp) important.
The generalized use of Pesticide S which kills the spiders and/or deprive them of Proie S is another threat. The regular reduction in the number of insects crushed on the vehicles is an indicator of the rarefaction of the food resource ( air plankton ) of the spiders, Chauve-souris and others Insectivore S.
Il seems finally that certain species can be sensitive to the ecological Fragmentation habitats by the roads (which they refuse to cross). In the night Environment, certain spiders drive out actively in particular in zone Tropical E. For a few decades have had also finds until the north of the moderate zones of the spiders normally Diurne S become very active the night. In fact species are sensitive in the light of the moon, but also artificial, weaving for example their fabrics around the standard lamps and surviving there longer, even all the winter in zone moderated thanks to the heat of the lamp. The impacts of these anthropic modifications hardly start to be studied (in particular via the phenomenon known as of luminous Pollution which are still for the spiders badly included/understood.
The cobweb was used and is still in certain parts of the world to facilitate the cicatrization of the cuts; “ Take spiders (Spider, at that time indicated also the fabric that the spiders make.), of the spider to put on vostre cut ” can one still read in the Dictionary of the French Academy (1re Édition of 1694)
industrialist Uses and soldier
Venoms of spiders were studied, in particular to produce Sérum S or drugs. The wire produced by certain spiders is more solid than steel, with equal thickness. (It is used to manufacture the reticle of the telescopes.) The gene which controls the production of it was insulated, and biotechnological industry tries to introduce it by Transgénèse into the Génome of other species to make a GMO able of it to produce a solid wire making it possible for example to make lighter waistcoats avoid-ball.
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