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 C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M 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: è Sangeeta Das, Research Scholar, Department of Zoology, Gauhati University & 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. C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M 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) i C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M 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 iii C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M 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 C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M 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 C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M 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 1 C O M M O N S P I D E R S F R O M S E L E C T P R O T E C T E D A R E A S O F U P P E R A S S A M 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.