INTRODUCTION SPIDERS DIVERSITY

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1 INTRODUCTION Spiders are ancient animals, emerged in carboniferous era, date back over 380 million years. They are abundant and widespread in almost all ecosystems and constitute one of the most important components of global biodiversity. Among animals spiders represent 18% of diversity. The order Araneae ranks seventh in total species diversity among all other groups of organisms. Spiders are interesting, intelligent and elegant creatures having predatory lifestyle. Most of the spiders have cannibalistic activity during courtship behavior. These carnivorous animals can run and jump very fast whenever required. Hence these are treated as cursorial creatures. These are pest in houses, but boost the crops, by killing harmful insects. Garden spiders are treated as friends of farmers, but farmers killing the spiders by spraying the pesticides. Spiders are an important part of the food chain, getting rid of unwanted insects and being food themselves for birds and other large insects and reptiles. Spiders are not insects by having two body sections, cephalothorax and abdomen as well as four pairs of legs. Most spiders consists four pairs of eyes and some are having three pairs. Wings and antennae are absent in spiders. Spiders are also unique as they possess spinnerets, which produce silk. They consists six types of silk producing glands at the end of abdomen. SPIDERS DIVERSITY The most characteristic features of spiders is their ability to produce silken threads. All spiders possess spinning glands which they use not only for making egg sacs (Cocoons) and draglines but also building traps and webs. In order to familiarize the spider systematics and ecology the following natural history of some spider families funnel web spiders (Agelenidae), orb-web spiders (Lycosidae), crab spiders (Thomisidae) jumping spiders (Salticidae) in brief will serve as an introduction to the succeeding chapters.

2 Funnel-web Spiders (Agelenidae) Funnel-web spiders are familiar to most of us. In Indian houses, for example, we find Tegenaria usually in the bathrooms, often trapped in the tub, where it cannot scale the smooth walls, aside from its considerable size (10mm body length). Tegenaria is quite conspicuous because of its long, hairy legs and the two long spinnerets protruding from its abdomen. Outdoors we can readily find somewhat smaller agelena in short grass or low bushes. The sheet webs of agelenids usually cover vegetation, or bridge the corners of buildings. The flat web narrows like a funnel on one end, forming a small silken tube. This retreat is open on both ends and most of the time the spider sits there in ambush; its out stretched front legs poised to receive vibrations from the web. When an insect blunders onto the web, the spider quickly darts out from its hideout, bites the victim, and carries it back. The actual feeding process always takes place inside the retreat. During the return to the tube the spider shows remarkably good orientation. For this reason funnel-web spiders have been favorite subject for sensory physiologists. The Water spider Argyroneta aquatica is also considered to be a member of the agelenid family. It is the only spider that constantly under water, rather than build a web; she attaches an air bubble to a water plant and uses it as a residence. She hunts mostly fly larvae of small crustaceans which she catches as she swims about freely under water. To catch the prey the spider must return to her diving bell. The abdomen of the water spider is always encased in a shiny air bubble, and this silvery reflection has earned her the scientific name Argyroneta (Greek, argyros=silver). From time to time air bag is replenished at the water surface. Thus the respiration of a water spider does not differ in principle from that of her land-living relatives. ORB-WEB SPIDERS (ARANEIDAE) The most impressive web design belongs to the orb weavers. The orb web of the common garden spider certainly represents the best-known type of all webs. The spider either sits right in the center of the web or hides in a retreat outside. Insects flying into the web become stuck with the sticky threads long enough for the spider to rush out from the hub to bite or wrap its victim (Sinha, 1951a, b).

3 Araneids are among the most successful spider families, as the enormous diversity of their spices (2,600) testifies. Thus it comes as no surprise to find that there are hundreds of structural variations on the orb-web design as well (Hingston, R.W.G 1927). The body structure of araneids may also considerably most notable are tropical orb weavers, which can be very colorful and exotically shaped. An orb web is typical not only for the Araneidae but also for two other spider families, the Tetragnathidae and the Uloborids build an orb web that is very similar to the webs of the araneids but that differs from them in one important aspect; the catching threads are not studded with glue droplets but are decorated with an extremely fine mesh of Cribellate silk (Tikader, B.K 1961). WOLF SPIDERS Wolf spiders are vagabonds that lie in ambush or freely hunt their prey. They are best recognized by their characteristic eye arrangements of four uniformly small eyes in the anterior row of eyes and two large median eyes in the posterior row. About 2,500 different spices occur all over the world, and they may vary quite a bit in size (Emerton, 1885). Smaller wolf spiders (4-10mm body length) roam freely among stones or low vegetation; only the larger representatives (Arctosa, Trochosa, Alopecosa; 10-20mm) dig burrows, (Gettmann W.W, 1976). A few species of wolf spiders (Aulonia, Hippasa), thought to be more primitive varieties, actually build webs reminiscent of the sheet webs of agelenids. The most famous wolf spider is certainly the Mediterranean tarantula (the name being derived from the Italian town of Taranto). True tarantulas (Lyctosa, Hogna) can reach an impressive 30mm of body length, but they are not related to the big tropical tarantulas, the mygalomorphs, also known as bird spiders (Gravelly, 1924). These tarantulas had long bad reputation as dangerous spiders. The ancient fear of their poisonous bite has been proven to be quite wrong. Probably any bites alleged to be from tarantulas were in fact inflicted by black widow spiders. Tarantulas live in silk-lined burrows in the soil. Some species even construct a sort of lid to close the tube, creating a burrow quite similar to that of the trapdoor spiders. At night tarantulas leave their burrows to crawl in search of insect. However, wolf spiders generally

4 do not actively run down their prey, as their name might suggest, but sit quietly and wait until a victim happens to come by (Ford M.J. (1978). Wolf spiders reach mainly to vibrations caused by the wing beat or by the characteristic walking pattern of the prey. Visual cues also play a role in detecting prey, but the eyes of wolf spiders perceive only a coarse image, and thus only objects very close by can serve as visual stimuli. This becomes apparent during courtship (Chamberlin, 1908), when the dark palps or front legs of the males are waved in a species-specific manner to attract the attention of the female. Female spiders are well known for their brood care. After laying their eggs they attach the egg case to their spinnerets and carry it around wherever they go (Sinha, 1951a). Some weeks later, just before the young spiderlings are ready to leave the cocoon, the mother rips the cocoon wall so that the young can emerge. As soon as the spiderlings have crawled out, they clamber onto their mother s back since they may number more than one hundred; they huddle there in several layers, they ride their mother s abdomen for about a week, then gradually disperse and take in food for the first time. Another group of spiders, the Ctenidae, was formerly considered a separate family, but recently has been classified as a subfamily of the Lycosidae (Homann, 1971). The most notorious Ctenid spider is the extremely poisonous and aggressive E.g.: Phoneutria fera, a less ferocious Ctenid spider, is cupiennius salei from central America. CRAB SPIDERS (Thomisidae) Crab spiders lie quietly in ambush and do not build webs. They sit motionless on leaves or in blossoms where with attentively outstretched legs they await landing insects. Their small eyes can produce sharp images only at very short distance, yet they perceive motions as far as 20cm away (Homann, 1934). If prey comes within reach (0.5-1cm) it is seized by the spider s strong front legs and then paralyzed by its poisonous bite. The victim is sucked out through the tiny bite holes. Since its exoskeleton remains intact, The victim appears practically unharmed when the spider has finished its meal.

5 Crab spiders may be very colourful they are often white or bright yellow and some are green. To some degree, Adult females can adapt their coloration to the background on which they sit (Basu, 1963, 1964, 1965). Even the less colourful species are usually well camouflaged and are hard to detect among the vegetation. Abdominal marking are very useful in determining the species (Daniel, 1962). The name crab spider comes from their ability to walk sideways very adroitly. The family philodromidae is often grouped together with the Thomisidae, although they bear only a superficial resemblance to crab spiders (Homann, 1975). Most notably, their legs are all of equal length, a feature typical of wandering spiders. JUMPING SPIDERS (salticidae) Atleast for an arachnologist the Jumpers are among the most attractive, if not congenial spiders. They are all rather small (3-10mm), with short stout legs and a square prosoma. Most conspicuous are the anterior eyes, which occupy the entire front of the carapace (Bastawade, 2002). Jumping spiders react very definitely to visual stimuli like passing insects or the approaching finger of an observer; first they turn to face the object, then they walk closer. They can distinguish different shapes at a distance of less than 10cms; these limits can be observed while the spider stalks prey, and also during courtship (Sadana, 1974). Males often possess conspicuously marked legs, which they use for display toward the females (Tikader, Malhotra, 1978). The hunting behavior of jumping spiders reminds one fact, for they stalk and pursue their prey until it is close enough for final pounce. Long jumps up to 16cms can be seen when a jumping spider flies. Before it jumps, the spider always attaches a safety thread to the ground, so that if it falls off an edge it will simply be held back by the threads and can quickly climb back the few centimeters to the point of take off. Some jumping spiders are ant-mimic. They look like and imitate ants (Tikader, 1973). Spiders belong to genus Phidippus have colourful chelicerae (Tikader, 1974a). Jumping spiders are more active during the day. They prefer sunshine, in cloudy or rainy weather they withdraw inside small silkee nests. These shelters not only protect them from the environment but also permit them to molt safely, to build egg cases, and to hibernate.

6 TENT-WEB SPIDERS The genus Cyrtophora belongs to Araneidae family spiders builds this type of webs. It is considered as a simplified orb-web. It is highly complex and non-sticky web. These webs are aligned horizontally, with a network of supporting threads above them. Centre of the web appears like a cone, with many support lines holding it. Cells in the tent web appear in rectangular. Ex: Cyrtophora kohensis. COB WEB SPIDERS The spiders belong to genus Steatoda, family Theridiidae are called triangulate cob web spiders. It is a common house spider. It consists of the triangle-shaped marking on the dorsal side of the abdomen. Ex: Steatoda triangulosa. SHEET-WEB SPIDERS The spiders belong to the Stiphidiidae and Linyphiidae families are called sheet-web spiders. These are very large spiders inhabiting in New Zealand. Their body length may be up to 2.5 cm with a leg span of 15 cm. They produce webs like a sheet up to a meter across. Their fangs are very long which measures one centimeter long. These are harmless spiders and bites are extremely rare. Ex: Cambridgea foliate. NURSERY WEB SPIDERS The genus Pisaura spiders belong to Pisauridae family are called nursery web spiders. When the eggs are about to hatch, a mother spider will build a nursery tent, put her egg sac inside and mother guard outside. Because of this peculiar behavior these spiders are named nursery web spiders. These spiders resemble wolf spiders, but they carry their egg sac with the jaws and pedipalps (Paik, 1969), whereas wolf spiders carry with spinnerets.

7 Ex: Pisaura mirabilis. LACE WEB SPIDERS The spiders belong to the genus Amaurobius, family Amaurobiidae are called lace web spiders. These are nocturnal spiders which wove bluish silk. This silk is combed into a frayed texture with a calamistrum, which present on the rear legs. The barbed hooks of insects get caught in the furry web, allowing the catching of much larger prey than the spider itself. Ex: Amaurobius fenestralis. CRIBELLATE ORB WEB SPIDERS The family Uloboridae includes cribellate orb weavers or hackled orb weavers. These spiders can weave hackled orb web with the special silk producing organ called cribellum. Cribellum is a narrow plate situated immediately in front of the spinnerets. These spiders also have a specilised comb called the calamistrum on the fourth metatarsus to pull and comb out the fine silk tangled out from the cribellum. These are non venomous spiders. Ex: Uloborus danolius. BIRD DROPPING SPIDERS The spiders belong to genus Celaenia and Mastophora, which comes under Araneidae family are called bird dropping spiders. These spiders resemble bird droppings. This type of mimicry is very useful to avoid predators, mainly birds. They can stay motionless on its web during the day; only night, spiders hang down from a single silk thread and releases a pheromone which mimics the sex smell released by female moths. When a moth comes near, the spider will capture it with their powerful front legs. These spiders have evolved an effective strategy against being eaten by birds and wasps. Its body mimics unappetizing bird droppings (Banks, 1914). They are also known as orchard spiders because they are so commonly seen on citrus and other orchards. Ex: Celaenia excavate.

8 CELLAR SPIDERS The spiders belong to Pholcidae family are called cellar spiders. They live in dark and damp recesses, in caves, under rocks and loose bark, buildings and cellars, hence the common name cellar spiders. They can live in dry places, such as household windows and attics. They are also called vibrating spiders, because when the spider is threatened by a touch, the spider vibrates rapidly and becomes blurred and difficult to focus on it (Subramanyam, 1940). For this reason pholcids are called vibrating spiders. Pholcids are also called daddy longleg spiders. It is purely misnomer, the name actually applied to harvestmens and crane flies, whose legs are very long (Stoliczka, 1869). Ex: Pholcus phalangioides COMB-FOOT SPIDERS Spiders of the family Theridiidae are called comb foot spiders. These spiders have a row of setae or bristles, on their fourth tarsi of legs. The setae help the spider wrap its silk around captured prey. These spiders have diverse life styles. Most species construct differently shaped three dimensional space webs. Some webs enable the spider to catch flying insects and consist of criss-cross viscid threads. Some other species make no web at all and may be found walking in leaf litter or in the ground. Ex: Argyrodes andamanensis RECLUSE SPIDERS These are also called fiddle-back spiders or violin spiders. The genus Loxosceles belong to Sicariidae family spiders are called recluse spiders. These are poisonous spiders. They can produce special venom called loxoscelin. These are generally in brown colours. Hence these spiders are called brown recluse spiders. These spiders usually have markings on the dorsal side

9 of the cephalothrax, with a black line coming from it that looks like a violin. Hence the name violin or fiddle back spiders. Ex: Loxosceles recluse PEACOCK SPIDERS The genus Maratus belongs to salticidae family spiders are called peacock spiders or gliding spiders. Males have flap-like extensions of the abdomen with white hairs that can be folded down. They are used for display during mating. While approaching the female, the male will vibrate his abdomen while waving raised legs and tail, and dance from side to side. The abdomen forms a white-fringed, circular field of colour. Then spider looks like a peacock. This is useful in sexual selection for spiders. Ex: Maratus volans. WIDOW SPIDERS The genus Latrodectus belongs to Theridiidae family spiders are called widow spiders. They are mostly in black coloured and identified by red or red-orenge hourglass-shaped markings on the abdomen of the female spiders. All are venomous spiders in this genus, can produce a neurotoxin called Latrotoxin, which causes the condition Latrodectism. These are very dangerous spiders, which kill humans with her bites. Ex: Latrodectus hesperus. SPITTING SPIDERS The family Scytodidae spiders are called spitting spiders. They catch their prey by spitting a fluid that congeals on contact into a venomous and sticky moss. This fluid produced from the venom glands in the chelicerae. It contains both venom and spider silk in liquid form. This liquid not only immobilizes the prey, but also has a venomous effect.

10 Ex: Scytodes thoracica. SCORPION SPIDERS These are also called flat or rock spiders. The genus Hemicloea, belongs to Gnaphosidae family are called scorpion spiders. They have flattened body with an elongate, oval abdomen, which resembles scorpions, hence the name scorpion spiders. They have three pairs of spinnerets. These spiders make a circular white disc as egg-sacs with a diameter of mm. they lay very large eggs which measures 1.2 mm in diameter. Ex: Hemicloea affinis. FISHING SPIDERS The genus Dolomedes, belongs to family Pisauridae spiders are called fishing spiders. They can walk on the surface of still bodies of water and catch the aquatic insects and fishes as the prey. These spiders hunt prey by waiting at the edge of a pond or stream, when they detect the ripples from prey, they run across the surface to subdue it using their front legs, which consists claws. After they inject venom to kill and digest the prey. They cannot walk on the smooth surfaces such as glass. Ex: Dolomedes tenebrosus. LYNX SPIDERS The family Oxyopidae includes lynx spiders. These long legged hunting spiders are capable of running very fast and jump on their prey like a cat. This is why their common name is lynx spiders. These are commonly found in agro-ecosystems. They feed on a agricultural pests. They are diurnal or nocturnal hunters with good vision. Long setae on their legs that assist them to blend in which spiky grasses (Gajbe, 1999). Among eight eyes, six eyes are arranged in hexagon like pattern, remaining two are smaller and situated in front and below the other six (Patel, 1977a). They can mimic the colour of the host plant. They are able to change colour to blend in with their surroundings (Sherriffs, 1927, 1928, 1929, 1951,).

11 Ex: Oxyopes elegans Common lynx spider., Peucetia viridana - Green lynx spider. SAC SPIDERS The spiders belong to Clubionidae family are called sac spiders. Sac spiders get their name from the little silk sacs in which they make to hide during the day. They also use the sacs to protect their eggs (Majumdar and Tikader, 1991). These are medium sized, pale yellow coloured spiders. All sac spiders have venom glands (Patel, 1973). They can cause injures to humans with bites. These are aggressive hunters. Ex: Clubiona trivialis. Some of the families consist of sac spiders. 1. Anyphaenidae:- African sea-shore sac spider 2. Mitargidae:- Long-legged, forest-floor sac spider 3. Liocrinidae:- Spiny-legged sac spider 4. Clubionidae:- Grass sac spider 5. Corinnidae:- Ant-like sac spider 6. Tengellidae:- Tengellid sac spider 7. Zorocratidae:- Zorocratid sac spider GROUND SPIDERS The spiders belong to Gnaphosidae family are called ground spiders. This family is the seventh largest known. They cannot spin a prey capture web and generally run prey down on the surface (Patel & Patel, 1975). They hunt at night and spend the day in a silken retreat (Chamberlin, 1922, 1933, 1935). Ground spiders have barrel-shaped anterior spinnerets. Another characteristic is an indentation in the endites. Ex: Zelotes laterelli SLENDER CRAB SPIDERS

12 The members of the genus Tibellus, in the family Philodromidae are called slender crab spiders. Because the bodies of these spiders are elongate and slender, hence the common name slender crab spiders. Species of this genus are present in Africa, America, Australia and Eurasia. These epigeal organisms live on soil surface and low vegetation, where they actively pursue their prey, as they do not make webs. These active hunters differ in many ways with sedentary crab spiders which belongs to Thomisidae family. Abdomen shows a large brown stripe in the middle of the back. The long and thin legs are stretched out along grass stems or leaves. The first two pairs of legs are forwardly directed. Ex: Tibellus elongates DEW DROP SPIDERS The species belongs to genus Argyrodes, family Theridiidae are called dew drop spiders or mirror spiders. The genus name is derived from greek argyros silver and odes like. These spiders have silvery markings on the body, which reflect light like a dew drop or mirror, hence the name dew drop spiders or mirror spiders. They are best known as kleptoparasites, means they steal other spiders prey. They invade and reside in their host s web, even though they can spin their own web. Ex: Argyrodes incursus TRAPDOOR SPIDERS The spiders belongs to Ctenizidae family are called true trapdoor spider. Some similar species are also called trapdoor spiders, such as the Liphistiidae, Barychelidae, Cyrtaucheniidae and some Idiopidae and Nemesiidae. Most of the medium-sized mygalomorph spiders that construct burrow with a cork-like trapdoor made of soil, vegetation and silk. Ex: Atrax robustus Following families are consist trapdoor spiders. 1. Ctenizidae:- Cork-lid trapdoor spiders 2. Barychelidae:- Baboon trapdoor spiders

13 3. Idiopidae:- Front-eyed trapdoor spiders 4. Nemesiidae:- Tube trapdoor spiders 5. Conothele:- Silken-tube trapdoor spiders 6. Liphistiidae:- Liphistid trapdoor spiders 7. Cyrtaucheniidae:- Cyrtauchenid trapdoor spiders

Contents. Glossary 31 Index 32. When a word is printed in bold, click on it to find its meaning.

Contents. Glossary 31 Index 32. When a word is printed in bold, click on it to find its meaning. Contents Mighty minibeasts 4 Spiders 5 What do spiders look like? 6 Different types of spiders 8 Where in the world are spiders found? 10 Habitats of spiders 12 Life cycles of spiders 14 How do spiders