1 ecology , behavior
1.1 non-predatory feeding
1.2 methods of capturing prey
1.3 defense
1.4 social spiders
ecology , behavior
non-predatory feeding
a jumping spider seen in chennai.
although spiders regarded predatory, jumping spider bagheera kiplingi gets on 90% of food solid plant material produced acacias part of mutually beneficial relationship species of ant.
juveniles of spiders in families anyphaenidae, corinnidae, clubionidae, thomisidae , salticidae feed on plant nectar. laboratory studies show deliberately , on extended periods, , periodically clean while feeding. these spiders prefer sugar solutions plain water, indicates seeking nutrients. since many spiders nocturnal, extent of nectar consumption spiders may have been underestimated. nectar contains amino acids, lipids, vitamins , minerals in addition sugars, , studies have shown other spider species live longer when nectar available. feeding on nectar avoids risks of struggles prey, , costs of producing venom , digestive enzymes.
various species known feed on dead arthropods (scavenging), web silk, , own shed exoskeletons. pollen caught in webs may eaten, , studies have shown young spiders have better chance of survival if have opportunity eat pollen. in captivity, several spider species known feed on bananas, marmalade, milk, egg yolk , sausages.
methods of capturing prey
the phonognatha graeffei or leaf-curling spider s web serves both trap , way of making home in leaf.
the best-known method of prey capture means of sticky webs. varying placement of webs allows different species of spider trap different insects in same area, example flat horizontal webs trap insects fly vegetation underneath while flat vertical webs trap insects in horizontal flight. web-building spiders have poor vision, extremely sensitive vibrations.
females of water spider argyroneta aquatica build underwater diving bell webs fill air , use digesting prey, molting, mating , raising offspring. live entirely within bells, darting out catch prey animals touch bell or threads anchor it. few spiders use surfaces of lakes , ponds webs , detecting trapped insects vibrations these cause while struggling.
net-casting spiders weave small webs, manipulate them trap prey. of genus hyptiotes , family theridiosomatidae stretch webs , release them when prey strike them, not actively move webs. of family deinopidae weave smaller webs, hold them outstretched between first 2 pairs of legs, , lunge , push webs as twice own body length trap prey, , move may increase webs area factor of ten. experiments have shown deinopis spinosus has 2 different techniques trapping prey: backwards strikes catch flying insects, vibrations detects; , forward strikes catch ground-walking prey sees. these 2 techniques have been observed in other deinopids. walking insects form of prey of deinopids, 1 population of deinopis subrufa appears live on tipulid flies catch backwards strike.
mature female bolas spiders of genus mastophora build webs consist of single trapeze line , patrol. construct bolas made of single thread, tipped large ball of wet sticky silk. emit chemicals resemble pheromones of moths, , swing bolas @ moths. although miss on 50% of strikes, catch same weight of insects per night web-weaving spiders of similar size. spiders eat bolas if have not made kill in 30 minutes, rest while, , make new bolas. juveniles , adult males smaller , not make bolas. instead release different pheromones attract moth flies, , catch them front pairs of legs.
a trapdoor spider in genus cyclocosmia, ambush predator
the primitive liphistiidae, trapdoor spiders of family ctenizidae , many tarantulas ambush predators lurk in burrows, closed trapdoors , surrounded networks of silk threads alert these spiders presence of prey. other ambush predators without such aids, including many crab spiders, , few species prey on bees, see ultraviolet, can adjust ultraviolet reflectance match flowers in lurking. wolf spiders, jumping spiders, fishing spiders , crab spiders capture prey chasing it, , rely on vision locate prey.
portia uses both webs , cunning, versatile tactics overcome prey.
some jumping spiders of genus portia hunt other spiders in ways seem intelligent, outflanking victims or luring them webs. laboratory studies show portia s instinctive tactics starting points trial-and-error approach these spiders learn how overcome new prey species. however, seem relatively slow thinkers , not surprising, brains vastly smaller of mammalian predators.
an ant-mimicking jumping spider
ant-mimicking spiders face several challenges: develop slimmer abdomens , false waists in cephalothorax mimic 3 distinct regions (tagmata) of ant s body; wave first pair of legs in front of heads mimic antennae, spiders lack, , conceal fact have 8 legs rather six; develop large color patches round 1 pair of eyes disguise fact have 8 simple eyes, while ants have 2 compound eyes; cover bodies reflective hairs resemble shiny bodies of ants. in spider species, males , females mimic different ant species, female spiders larger males. ant-mimicking spiders modify behavior resemble of target species of ant; example, many adopt zig-zag pattern of movement, ant-mimicking jumping spiders avoid jumping, , spiders of genus synemosyna walk on outer edges of leaves in same way pseudomyrmex. ant-mimicry in many spiders , other arthropods may protection predators hunt sight, including birds, lizards , spiders. however, several ant-mimicking spiders prey either on ants or on ants livestock , such aphids. when @ rest, ant-mimicking crab spider amyciaea not closely resemble oecophylla, while hunting imitates behavior of dying ant attract worker ants. after kill, ant-mimicking spiders hold victims between , large groups of ants avoid being attacked.
defense
threat display sydney funnel-web spider (atrax robustus).
there strong evidence spiders coloration camouflage helps them evade major predators, birds , parasitic wasps, both of have color vision. many spider species colored merge common backgrounds, , have disruptive coloration, stripes , blotches break outlines. in few species, such hawaiian happy-face spider, theridion grallator, several coloration schemes present in ratio appears remain constant, , may make more difficult predators recognize species. spiders insufficiently dangerous or unpleasant-tasting warning coloration offer benefit. however, few species powerful venoms, large jaws or irritant hairs have patches of warning colors, , actively display these colors when threatened.
many of family theraphosidae, includes tarantulas , baboon spiders, have urticating hairs on abdomens , use legs flick them @ attackers. these hairs fine setae (bristles) fragile bases , row of barbs on tip. barbs cause intense irritation there no evidence carry kind of venom. few defend against wasps including networks of robust threads in webs, giving spider time flee while wasps struggling obstacles. golden wheeling spider, carparachne aureoflava, of namibian desert escapes parasitic wasps flipping onto side , cartwheeling down sand dunes.
social spiders
a few spider species build webs live in large colonies , show social behavior, although not complex in social insects. anelosimus eximius (in family theridiidae) can form colonies of 50,000 individuals. genus anelosimus has strong tendency towards sociality: known american species social, , species in madagascar @ least social. members of other species in same family several different genera have independently developed social behavior. example, although theridion nigroannulatum belongs genus no other social species, t. nigroannulatum build colonies may contain several thousand individuals co-operate in prey capture , share food. other communal spiders include several philoponella species (family uloboridae), agelena consociata (family agelenidae) , mallos gregalis (family dictynidae). social predatory spiders need defend prey against kleptoparasites ( thieves ), , larger colonies more successful in this. herbivorous spider bagheera kiplingi lives in small colonies protect eggs , spiderlings. widow spiders (genus latrodectus), notoriously cannibalistic, have formed small colonies in captivity, sharing webs , feeding together.
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