Common Spiders

2015·116.2 MB·Assamese

by  Sangeeta Das

COMMON SPIDERS
FROM SELECT PROTECTED AREAS OF UPPER ASSAM
Assam State Biodiversity Board
COMMON SPIDERS
FROM SELECT PROTECTED AREAS OF UPPER ASSAM
Assam State Biodiversity Board
COMMON SPIDERS FROM SELECT PROTECTED AREAS OF UPPER ASSAM
COMMON SPIDERS
FROM SELECT PROTECTED AREAS OF UPPER ASSAM
Published by:
Assam State Biodiversity Board
Rehabari, Guwahati -781008
Copyright:
© 2015 Assam State Biodiversity Board
Fieldwork: Phalgun Chetia, Research Scholar, Department of Life Sciences
Dibrugarh University.
Text Development:
Sangeeta Das, Research Scholar, Department of Zoology, Gauhati University &
(cid:1) è 2 É
Dr. O. S. Devi, Scientific Officer, Assam State Biodiversity Board.
Photographs:
Phalgun Chetia, Sangeeta Das & Dr. Mazedul Islam
Cartoons:
Debolina Dey, Technical Assistant - ASBB
Editing:
Dr. Ranjana Gupta, IFS, Additional PCCF, Wetlands, O/o PCCF & HoFF, Assam.
Dr. O. S. Devi & Dr. Mazedul Islam, Technical Assistant - ASBB
Design & Layout:
Anjan J. Mahanta
Printing & binding:
Ramdhenu Media Services Pvt. Ltd., Guwahati
ISBN: 978-81-932243-0-4
ACKNOWLEDGEMENT:
Assam State Biodiversity Board sincerely acknowledges the contributions made by researchers
and nature lovers for providing relevant information, photographs and articles, personally and
through social media.
COMMON SPIDERS FROM SELECT PROTECTED AREAS OF UPPER ASSAM
Shri Subhash Chandra Das, IAS
Chairman, Assam State Biodiversity Board
Addl. Chief Secretary, Assam
FOREWORD
Life on earth is enchanting, its diversity intriguing and the inter-
relatedness of species awe-inspiring. The more we dwell into the web
of life, the more fascinating it becomes. More so, for the life-forms that
are less explored.
As a part of its mandate the Board is sponsoring studies into lesser-
known species for highlighting their ecological and economic
significance. The study into varieties of spiders is one such step.
I congratulate everyone involved in this endeavor and hope that
the book will make an interesting reading.
(S. C. Das)
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COMMON SPIDERS FROM SELECT PROTECTED AREAS OF UPPER ASSAM
COMMON SPIDERS FROM SELECT PROTECTED AREAS OF UPPER ASSAM
PREFACE
Spiders are fascinating creatures present practically everywhere.
They may look small and insignificant, but they are important
predators and prey on a multitude of other animals. They are great
garden allies too.
While some spiders are social, most are solitary and interact with
each other during territorial guarding or at the time of mating. Spiders
eat insects, thus, help in controlling insect populations. They are an
important source of food for a variety of birds, lizards, wasps, and
mammals, especially in deserts. Spider-silk is said to be the strongest
natural material. The venom harvested from spiders helps control and
treat several diseases. Yet spiders are not considered sanctified. They
are blamed for their creepy looks and bites, albeit their bites are not
lethal to healthy adults.
A few years back in Assam there were reports of human deaths
allegedly due to spider-bite. Unfounded fear prevailed and at places
there were rampant killing of spiders. A study commissioned by the
Board revealed that venom of the 'culprit-spider' was not lethal enough
to cause any death, least of all of human beings. But the hatred for
spiders continues. We still consider cob-webs as symbol of
unkemptness. Sighting of spiders or contact with them is often
detested. The fear of spiders, arachnophobia, is one the most common
fears and, at times, is so acute that it needs professional help.
This publication is an attempt to unravel the beautiful world of
spiders, their varieties, usefulness, ecological significance, and
vulnerabilities by describing common spiders from select protected
areas of Upper Assam.
I hope readers will find this publication interesting and
informative.
(A. K. Johari)
Member Secretary,
Assam State Biodiversity Board
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COMMON SPIDERS FROM SELECT PROTECTED AREAS OF UPPER ASSAM
CONTENTS
Foreword I
Perface III
Introduction to Spiders 1
Keys for spider identification 5
Parts of a typical spider 5
Some important taxonomic keys
for identification 7
Spider Eye Arrangement 7
Web as Identification Key 9
Spider Guild Structure 11
Study Area 12
List of species described in this book 15
SPECIES ACCOUNTS
Araneidae 17
Clubionidae 47
Corinnidae 51
Eutichuridae 55
Hersiliidae 59
Linyphiidae 63
COMMON SPIDERS FROM SELECT PROTECTED AREAS OF UPPER ASSAM
Lycosidae 67
Nephilidae 71
Oxyopidae 79
Pholcidae 87
Salticidae 93
Scytodidae 119
Sparassidae 123
Tetragnathidae 131
Theraphosidae 141
Theridiidae 145
Thomisidae 153
Photo Plates 161
Some fallacies and facts about spiders 170
Some interesting information
about spiders 171
Some venomous spiders of the world 175
Glossary 179
References 184
Index 186
COMMON SPIDERS FROM SELECT PROTECTED AREAS OF UPPER ASSAM
INTRODUCTION TO SPIDERS
Spiders are air breathing animals belonging to the Phylum
Arthropoda, the largest group in the animal kingdom. They fall under
the largest order Araneae of the Class Arachnida which ranks 7th in the
total species diversity among all other orders of organisms. They are
found on every continent except Antarctica and are known to colonize
nearly every habitat. According to the World Spider Catalog (Version
17.0), 45,834 valid spider species are currently recorded under 3,977
genera and 114 families so far.
Spiders have 4 pairs of legs and a body divisible into two distinct
parts namely the cephalothorax or prosoma and the abdomen or
opisthosoma, joined by a small stalk called pedicel. Pedicel is a
characteristic feature of spiders by which they can be differentiated
from other arachnids. They also possess unique body appendages
called spinnerets which are situated at the end of the abdomen.
Spinnerets release silk from up to 6 different types of silk glands located
in the spider's abdomen. Unlike insects, spiders do not have antennae.
Spiders occur in a large range of sizes. The smallest, Patu marplesi is
less than 0.3 mm (0.01 in) in body length. The largest and heaviest
spiders occur among tarantulas, which can have body lengths up to 90
mm (3.5 in) and leg spans up to 250 mm (9.8 in).
All known species of spiders are predators, preying on insects and
other arthropods except for a herbivorous species Bagheera kiplingi
which was described in 2008. They use a wide range of strategies to
capture prey such as trapping it in sticky webs, lassoing it with sticky
bolas, mimicking the prey to avoid detection, or running it down. Some
other species detect prey mainly by sensing vibrations. Cannibalism is
also very common among spiders. Male spiders of most species
indulge in complex courtship rituals before mating, only to avoid being
eaten by the females.
A minority of species are social, building communal webs that may
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COMMON SPIDERS FROM SELECT PROTECTED AREAS OF UPPER ASSAM
house anywhere from a few to 50,000 individuals. They are also known
to exhibit social behavior such as co-operative hunting and food-
sharing. The life span of most spiders is estimated to be about two years
but some species such as tarantulas are reported to live up to 25 years in
captivity.
They are prolific breeders and have very high population growth
rate. If not for some predators such as birds, lizards, frogs, toads,
shrews, hunting beetles, wasps, ants and larger insects who feed on the
spiders, they may dominate and overthrow us from the face of earth.
Spiders are divided into 2 general groups, web builders and non-
web building spiders. All spiders produce silk, but all do not make
webs. Web-weaving spiders build webs to catch prey and they live on
or near their web. There are different types of webs which sometimes
act as species identification tool. The sheet web, orb web, tangle web,
funnel web, tubular web and dome or tent web are some remarkable
webs made by spiders. The most common type of web visible around
our home is the orb web, so called because of its circular shape,
resembling a giant wheel. Non-web building species are the wandering
spiders that search out for prey, or ambushing spiders, which sit and
wait for prey to come close to them and water spiders, that trap air
bubbles under their abdomen and take their air-chamber below the
water to capture prey.
Spiders have up-to 6 silk glands in their spinneret which emits the
silk. Each gland produces a thread for making webs or for special
purposes such as a trailed safety line, for trapping prey or for self
defence. They use different gland types to produce different silks, and
there are reports of some spiders capable of producing up to 6 - 7
different types of silk during their lifetime. It was reported that the
proteinaceous spider silk is similar in tensile strength to nylon and
biological materials such as chitin, collagen and cellulose, but is much
more elastic. Thus, it is being used in varieties of purposes such as
textiles, medicine and fishing. But it is very difficult to extract and
process substantial amount of spider silk. The largest known piece of
cloth made of spider silk is an 11-by-4-foot (3.4 by 1.2 m) textile with a
golden tint made in Madagascar in 2009. From many decades scientists
are trying to develop body armour out of spider silk. If successful, this
would mean ultra-lightweight, super-strong, flexible body armour
that would provide highly improved protection for soldiers and other
law enforcement officers.
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