Spiders: Diversity, Distribution, and Conservation

Spiders are invertebrate animals with two body segments, four pairs of legs and without wings and mouth parts. They exclusively feed on insect pests and protect the cultivated crops. They are at the top of the lower food web in any ecosystem. Spiders main

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Spiders: Diversity, Distribution, and Conservation Ganesh Vankhede, Priyanka Hadole, and Akshay Kumar Chakravarthy

Abstract

Spiders are invertebrate animals with two body segments, four pairs of legs and without wings and mouth parts. They exclusively feed on insect pests and protect the cultivated crops. They are at the top of the lower food web in any ecosystem. Spiders maintain ecosystem balance. Nearly 45,000 spider species are known worldwide. Spider silk is one of the best biomaterial on the earth having antimicrobial properties, high tensile strength and is biocompatible with humans. All spiders produce silk, a solid protein strand expelled from spinnerets most normally found at tip of the abdomen. Silk is used to trap insects in webs, by many species, and they hunt freely. It is also used in climbing, form smooth outer covering walls for burrows, and build egg sacs, wrap prey, and temporarily hold sperm, among other applications. An abnormal fear of spiders (arachnophobia) is one of the most common phobias, and spiders are often looked at as something to be eliminated. Spiders have an awesome scope of variety in way of life, albeit all are savage. Arachnids give a substantial number of free biological system administrations. Keywords

Predatory • Ecosystem balance • Spider silk • Threats

G. Vankhede (*) • P. Hadole Department of Zoology, Sant Gadge Baba Amravati University, Amravati 444602, Maharashtra, India e-mail: [email protected]; [email protected] A.K. Chakravarthy Division of Entomology and Nematology, Indian Institute of Horticultural Research (IIHR), Hessarghatta Lake Post, Bengaluru 560089, Karnataka, India © Springer Science+Business Media Singapore 2016 A.K. Chakravarthy, S. Sridhara (eds.), Arthropod Diversity and Conservation in the Tropics and Sub-tropics, DOI 10.1007/978-981-10-1518-2_8

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Introduction

Spiders are arthropods having four pairs of legs, eight eyes, and the capacity to secrete silk immediately after birth. They are cosmopolitan. Spiders secrete venom, not toxic to humans but show cytotoxicity. Many spiders can prepare the web but not all. Though spiders have eight eyes, there are some spiders with six or four or two eyes only. Spiders living in caves have no eyes. The sperm of the male spider shows 9 ± 2 arrangement of microtubules like those in prokaryotes, and hence according to one theory, it is thought that the spiders have come from other planets. The primary distinctions among insects and arachnids are the pedicel between the cephalothorax and the gut and the nearness of spinnerets (Marina and Kleber 2008). All spiders aside from families Uloboridae and Holarchaeidae can infuse venom to secure themselves or to murder and condense prey. Only up to 200 species, however, have bites that pose health problems to humans (Diaz 2004). Several specie's nibbles might be difficult; however it will not create enduring health concerns. Be that as it may, in satisfying their own particular individual reason for survival, upkeep, and