spider spiders order air breathing legs venom largest order rank seventh total species diversity orders organisms spiders found worldwide continent antarctica established nearly habitat exceptions air sea colonization november spider species families recorded scientific community families classified evidenced different classifications proposed spiders differ usual body segments fused abdomen joined small cylindrical unlike insects spiders antennae primitive group spiders centralized nervous systems fused mass unlike spiders muscles limbs instead extend hydraulic pressure bear modified silk types spider vary widely size shape sticky thread appears spiral web earliest forms spiders produce abundant diverse web spiders spider like silk producing appeared period million years ago animals apparently lacked true spiders found rocks million years ago similar primitive surviving main groups modern spiders appeared period million years ago species described known species predators insects spiders large species birds spiders use wide range strategies capture prey trapping sticky sticky mimicking prey avoid detection running detect prey mainly sensing vibrations active hunters acute vision hunters genus signs intelligence choice tactics ability develop new ones spiders narrow food flooding digestive grinding bases true jaws male spiders identify variety complex courtship rituals avoid eaten females males species survive limited mainly short life spans females silk egg cases contain hundreds eggs females species care young example carrying sharing food minority species social building communal house individuals social behavior ranges widow spiders operative hunting food sharing spiders live years spiders live years captivity venom species dangerous humans scientists researching use spider venom medicine non spider silk provides combination strength superior synthetic materials spider silk genes inserted mammals plants silk factories result wide range behaviors spiders common symbols art mythology combinations patience cruelty creative powers abnormal fear spiders called description body plan spiders bodies limbs covered cuticle proteins heads composed segments fuse development embryo bodies consist sets segments serve similar functions foremost called complete fusion segments insect form separate head rear called abdomen spiders abdomen connected small cylindrical section pattern segment fusion forms heads unique normally head segment disappears early stage development lack antennae typical fact ahead mouth pair lack function directly jaws mouth called serve different functions different groups spiders members group sections feeding spiders sections terminate generally fold away upper sections use upper sections generally thick filter solid food spiders liquid food generally form large claws capturing prey spiders fairly small bases act extension mouth addition male spiders enlarged sections sperm transfer spiders abdomen joined small cylindrical enables abdomen independently producing silk upper surface covered single convex underside covered flat plates abdomen soft egg shaped shows sign primitive living members plates upper surface circulation like spiders reduced small areas round reproductive systems place largely taken cavity runs length body blood flows heart tube upper body act non return allowing blood enter heart prevent leaving reaches end spiders occupies upper abdomen blood discharged opens rear end abdomen branching pass open parts spiders open systems blood spiders book lungs contains respiratory pigment oxygen transport efficient spiders developed different respiratory based book lungs system spiders pairs book lungs filled openings ventral surface abdomen allow air enter oxygen case basal spiders like family remaining members group anterior pair book lungs intact posterior pair breathing organs partly fully modified oxygen directly tissue organs system likely evolved small ancestors help resist originally connected surroundings pair openings called majority spiders pair fused single middle moved backwards close spiders generally higher rates better water conservation spiders environmental temperatures affect activity feeding uniquely final sections spiders great majority spiders use venom prey venom roots family lost venom kills prey silk instead like including spiders narrow gut cope liquid food spiders sets filters use different systems external pump digestive prey suck tissues prey gut eventually leaving prey grind prey pulp bases flooding species bases form cavity holds food processing stomach acts pump sends food deeper digestive system mid gut bears digestive compartments exit extract nutrients food abdomen dominated digestive system found spiders convert waste products acid dry material little tubes extract blood dump chamber expelled production acid removal water feature evolved independently live far away water example insects develop completely different parts embryo primitive spiders sub order order retain ancestral little use large amounts water waste products central nervous system basic central nervous system consists pair nerve running gut paired local control centers segments brain formed fusion head segments ahead mouth encircled primitive sole surviving family spiders centralized nervous system typical segments fused largely filled nervous tissue abdomen abdomen rear remain despite relatively small central nervous system spiders like exhibit complex behaviour including ability use trial error approach sense organs eyes spiders pairs eyes area arranged patterns vary family pair type called pigment cup little eyes capable detecting direction light coming shadow cast walls cup main eyes spiders heads pigment cup capable forming images eyes thought derived compound eyes ancestral longer separate typical compound eyes unlike main eyes spiders secondary eyes detect light reflected reflective wolf spiders spotted torch light reflected hand jumping spiders secondary eyes jumping spiders visual exceeds factor far best vision insects fact human eye times jumping spider achieve like series lenses layer ability swivel eyes integrate images different stages scan scanning integrating processes relatively slow spiders reduced number eyes eyes numerous missing pair eyes anterior median line species eyes cave dwelling species eyes possess eyes incapable sight senses spiders block information outside world penetrated sensors connections sensors nervous system fact spiders modified elaborate sensors touch sensors called respond different levels force strong contact weak air currents chemical sensors provide taste smell means carry large number sensitive contact chemicals air borne female spiders joints limbs detect forces vibrations web building spiders mechanical chemical sensors important eyes eyes important spiders hunt actively like spiders lack balance acceleration sensors rely eyes tell way sensors report force exerted muscles degree bending body joints understood hand little known internal sensors spiders legs spider consists seven distinct parts closest leg segment short works following long segment spider knee acts connects thought foot sorts ends points depending family spider belongs use muscles attached inside limbs spiders groups use hydraulic pressure extend system inherited pre ancestors muscles spider legs located hip joints bordering result spider extend legs legs dead spiders spiders generate pressures times resting level extend legs jumping spiders jump times length suddenly increasing blood pressure fourth pair legs larger spiders use legs unlike smaller jumping spiders depend muscles generate force jumps spiders hunt actively relying dense fine hairs paired claws tips legs known consist ends split branches enable spiders walk vertical glass upside ceilings appears grip contact extremely thin layers water surfaces spiders like legs surface walking running silk production abdomen modified form usually pairs short silk connected silk types silk producing different type silk silk mainly composed protein similar insect silk initially liquid exposure air result drawn changes internal structure protein similar strength biological materials elastic words stretch breaking losing shape spiders modified produces single fine fiber fibers pulled like set tip combined composite thread effective insects earliest spiders produced silk capable capturing insects spiders developed silk coated sticky modern groups spiders lost silk feet species build catch prey use silk ways sperm eggs safety rope nest building young species reproduction life cycle spiders reproduce sexually internal indirect words sperm inserted female body male intermediate stage unlike land living male spiders produce ready packages sperm spin small sperm transfer sperm special like structures organs borne tips mature males male signs female nearby checks species ready mate example species produce safety ropes male identify species sex objects smell spiders generally use elaborate courtship rituals prevent large females eating small males male smaller worth eating web weaving species precise patterns vibrations web major rituals patterns touches female body important spiders hunt actively female gestures dances male important jumping spiders excellent courtship successful male sperm female opening known underside abdomen female reproductive tracts vary simple tubes systems include seminal females store sperm release ready males genus maturation enter adult life male body mass species improves mobility species remaining torn female separated remains attached female hours apparently continues function independently meantime female feeds male cases female australian spider kills eats male second female opening fact males operate trying females observation shows male opportunity mate lucky ones increase likely number offspring ensuring females fed males species survive limited mainly short life spans live mates females lay eggs silk egg maintain fairly constant humidity level species females die females species protect hiding nests carrying dragging baby spiders pass stages inside egg hatch small sexually immature similar shape adults spiders care young example wolf spider brood rough mother females species respond begging behaviour young giving prey provided longer struggling food like spiders grow cuticle skin stretch species males mate newly females weak dangerous males spiders live years live captivity years size spiders occur large range sizes smallest colombia body length largest heaviest spiders occur body lengths leg spans coloration classes pigment identified spiders detected characterized common animals apparently absent species legs modified process resulting brown coloration found example resulting green color responsible white markings european garden spider species accumulated specialized cells called genera creates appearance originally end product protein blocked spiders leading increase storage structural colors occur species result scattering interference light example modified scales white results hairs reflecting light areas modified cuticle act light ecology behavior non predatory feeding spiders generally regarded predatory jumping spider gets food fairly solid plant material produced mutually beneficial relationship species juveniles spiders families feed plant laboratory studies deliberately extended periods periodically clean feeding spiders prefer sugar solutions plain water indicates seeking nutrients spiders nocturnal extent consumption spiders contains minerals addition studies shown spider species live longer available feeding avoids risks struggles prey costs producing venom digestive species known feed dead web silk shed caught eaten studies shown young spiders better chance survival opportunity eat captivity spider species known feed milk egg yolk methods capturing prey best known method prey capture means sticky varying placement allows different species spider trap different insects area example flat horizontal trap insects fly vegetation underneath flat vertical trap insects horizontal flight web building spiders poor vision extremely sensitive vibrations females water spider build underwater diving bell fill air use prey mating raising offspring live entirely bells catch prey animals touch bell threads anchor spiders use surfaces lakes ponds detecting trapped insects vibrations cause struggling net casting spiders small manipulate trap prey genus family stretch release prey strike actively family smaller hold pairs legs push twice body length trap prey increase area factor experiments shown different techniques trapping prey backwards strikes catch flying insects vibrations forward strikes catch ground walking prey sees techniques observed walking insects form prey population appears live mainly flies catch backwards strike mature female spiders genus build consist single line patrol construct single thread tipped large ball wet sticky silk chemicals resemble swing miss strikes catch weight insects night web weaving spiders similar size spiders eat kill minutes rest new juveniles adult males smaller instead release different attract flies catch pairs legs primitive spiders family ambush predators closed surrounded networks silk threads alert spiders presence prey ambush predators aids including crab spiders species prey bees adjust match flowers wolf spiders jumping spiders fishing spiders crab spiders capture prey chasing rely mainly vision locate prey jumping spiders genus hunt spiders ways intelligent victims laboratory studies tactics starting points trial error approach spiders learn quickly overcome new prey species relatively slow surprising brains vastly smaller predators spiders face challenges generally develop false mimic distinct regions body wave pair legs form heads mimic antennae spiders lack conceal fact legs develop large color patches round pair eyes disguise fact generally simple eyes ants compound eyes cover bodies reflective hairs resemble shiny bodies ants spider species males females mimic different species female spiders usually larger males spiders modify behavior resemble target species example adopt pattern movement mimicking jumping spiders avoid jumping spiders genus walk outer edges leaves way spiders protection predators hunt sight including birds spiders mimicking spiders prey ants ants livestock rest mimicking crab spider closely resemble hunting behavior dying attract worker ants kill mimicking spiders hold victims large groups ants avoid attacked defense strong evidence spiders coloration camouflage helps evade major predators birds parasitic good color vision spider species colored merge common backgrounds coloration stripes break outlines species hawaiian happy face spider coloration schemes present ratio appears remain constant difficult predators recognize species spiders dangerous unpleasant warning coloration offer benefit species powerful large jaws hairs patches warning colors actively display colors threatened family includes spiders hairs use legs flick attackers hairs fine fragile bases row tip cause intense evidence carry kind venom defend including networks robust threads giving spider time flee struggling obstacles golden spider desert escapes parasitic sand dunes social spiders spider species build live large colonies social behavior complex social insects family form colonies individuals genus strong tendency known american species social species madagascar somewhat social members species family different genera independently developed social behavior example belongs genus social species build colonies contain thousand individuals operate prey capture share food communal spiders include species family family family social predatory spiders need defend prey thieves larger colonies successful spider lives small colonies help protect eggs widow spiders genus formed small colonies captivity sharing feeding web types consistent relationship classification spiders types web build species genus build similar significantly different correspondence spiders classification chemical composition evolution web construction words use similar techniques remotely related species rampant web designs spinning behaviors produce best understood basic radial spiral sequence visible sense direction required build inherited common ancestors spider groups majority spiders build non thought sticky web evolutionary innovation resulting appears non spiders sub group evolved web spiders non spiders species times abundant web spiders greater success dominant predators spiders prefer attack spiders flat half potential prey hit escape web perform functions prey intersection absorbing momentum breaking stopping trapping prey sticking retention single design best prey example wider lines increase web area ability intercept prey reduce stopping power retention closer larger sticky thicker lines improve retention easier potential prey avoid web day consistent differences built use day built use night fact simple relationship web design features prey capture weaving species takes wide range prey spiders usually center spiders downwards faster upwards obvious direction spider retreat avoid predators hub usually offset direction horizontal fairly common despite effective retaining prey vulnerable damage rain falling debris researchers suggested horizontal offer advantages reduced vulnerability wind damage reduced visibility prey flying upwards lighting sky enabling catch insects slow horizontal flight single explanation common use horizontal spiders attach highly visible silk bands called decorations field research suggests decorative bands captured prey hour laboratory study showed spiders reduce building decorations sense presence predators unusual variants web evolved including attachment lines surface water possibly trap insects surface twigs centers possibly hide spiders predators ladder like appear effective catching significance variations unclear took web spiders space test web spinning capabilities zero gravity produced sloppy adapted quickly spiders spiders members family irregular dimensional popularly known evolutionary trend reduction sticky silk leading total absence species construction days types generally horizontal uneven sheets stopping threads insects hit stopping threads fall sheet shaken spider held sticky threads sheet spider attack evolution fossil record fossil record spiders considered poor species described fossils spiders bodies soft vast majority fossil spiders found preserved amber oldest known amber contains fossil dates million years ago early cretaceous period addition preserving spiders anatomy fine detail pieces amber spiders mating killing prey producing silk possibly caring young cases amber preserved spiders egg occasionally prey attached oldest fossil web found far million years old earlier spider fossils come places conditions exceptionally suited preserving fairly soft tissues oldest known exclusively terrestrial million years ago period triangular abdomen legs pair million years ago period bears earliest known silk producing hailed spider time discovery mounted underside abdomen modified mobility important building similar true spiders probably silk lining nests producing egg cases building largest known fossil spider million years ago recorded china body length inch spiders members primitive group represented late million years ago period million years ago saw rapid flying insects fossil spiders period main groups modern spiders appear million years ago appear members family modern members include notorious sydney funnel web spider appear adapted building funnel shaped catch jumping insects account great majority modern spiders including familiar shaped cretaceous periods provide large number fossil spiders including representatives modern families family tree agreed spiders members group organisms form clade consisting common ancestor descendants debate closest evolutionary relatives evolved ancestral marine animals right based analysis views include proposals closely related extinct marine like spiders spiders group appearance multi way tree right shows relationships groups involved lack features including backward pointing mouths jaw bases bases legs features ancestral feeding system instead mouths point forwards downwards means breathing air spiders distinguished groups characteristics including males specially adapted sperm transfer taxonomy spiders divided contains nearly living species spiders order identified currently grouped families genera living members primitive family found southeast_asia china japan construct silk lined thin species genus build silk tubes second emergency exit members genus run silk tunnels help detect approaching prey genus instead rely built vibration sensors spiders genus venom venom outlets tip extinct families found rocks far found rocks classified members appeared period generally heavily built large robust known examples include spiders funnel web spiders spend majority time run silk build capture prey produce silk use instant silk surfaces strands silk makes web construction difficult rarely balloon air currents transport populations form addition capable frogs small mammals addition accounting spider species known true spiders include web spiders wolf spiders jumping spiders known spider distinguished having oppose cross action contrast nearly parallel alignment spiders people spider bites spiders widely feared species dangerous people spiders bite humans self defense produce worse effects bite bee sting medically bites spiders widow spiders flee bite trapped easily arise accident funnel web spiders defensive tactics include display venom rarely resulted known human deaths years deemed world dangerous spiders clinical venom grounds claim attributed brazilian wandering spider frequent accidents reliably reported deaths spider bites 20th century alleged cases spider bites represent incorrect difficult check effectiveness treatments genuine bites benefits humans spider alternative conventional deadly insects great majority harmless australian funnel web spiders promising source world insect opportunity develop immunity venom funnel web spiders thrive captivity easy milk possible target specific engineering genes production spider species cotton maya use created species treatment condition term wind symptoms include chest pain possible medical uses spider investigated treatment cardiac disease strokes found venom researched determine effectively treatment cardiac muscular spider silk light strong attempts produce goats milk leaves plants means genetic engineering spiders food cooked spiders considered southern venezuela provided highly hairs spiders main defense system removed specific abnormal fear spiders reminiscent spiders spider like shapes common specific statistics women men symptoms exaggerated form response helped early humans survive cultural phenomenon common predominantly european societies spiders symbolism culture spiders focus stories cultures centuries patience hunting technique setting waiting prey bites italian dance rid young woman effects spider bite web spinning caused association spider creation myths ability produce worlds depictions people ancient peru nature placed emphasis animals depicted spiders art
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