Preface Of the million or so animal species that have so far been described, about 85 percent are insects; there are estimated to be 200 million of them for every living person. To put it another way, there are some 10,000 million insects living in each square kilometer of habitable land on Earth or 26,000 million per square mile. Insects also predominate overwhelmingly among the terrestrial arthropods that are the subject of this book. What is more, the land-dwelling, jointed-limbed animals without backbones also include the millipedes and centipedes, and the spiders, scorpions, ticks and mites; for example, in rural southern England there may be as many as 5 million spiders per hectare (12.5 million per acre). These figures are for known species only: recent surveys in tropical forests suggest that there may be as many as 25 to 30 million species of arthropod in the world, most of which remain undescribed! Until recently, most studies of arthropods were primarily or entirely descriptive -- and rightly so in the face of such bewildering diversity. In the last 50 years, however, the relatively new disciplines of population and behavioral ecology have embraced the arthropods and revealed them in a new light. Population ecology has shown just how important the relationships between arthropods and other living things are. Behavioral ecology shows that many arthropods have behavior normally only associated with birds and mammals. Arthropods, and especially the insects, are, in fact, a vital part of the survival kit of Planet Earth, having a commanding presence in the dynamic processes that maintain our ecosystems. They dispose of dead vegetation, animal corpses, and dung, and are the major herbivores, processing and returning vast amounts of nutrients to the soil. As pollinators of flowers, they are vital links in the cycle of plant generations. Yet ticks, fleas, and a variety of flies exert a negative influence on human ecology, through the diseases they transmit to humans and their livestock, while many mites and insects devastate crops and trees. There is now a growing awareness that our survival as a species may well depend on a greater understanding of the diversity of living things and their conservation. The greatest urgency lies with the wet forests of the tropics, home of half of all plant and animal species. It is a humbling thought that our primate ancestors inherited a range of habitats largely shaped and maintained by the interactions of arthropods with plants and other animals. In a real sense we began our road to humanity by exploiting opportunities provided by courtesy of the arthropods. It is even more humbling to ponder the thought that this planet can survive without man but not, in its present form, without the arthropods. Underlining the never-ending work of insect taxonomists is the very recent discovery of a new order of insects, the Mantophasmatodea, too recent, indeed, to be dealt with comprehensively in this volume. Comprising two known genera, Raptophasma from fossil material in Baltic amber and Mantophasma from tropical Africa, members of this order are wingless carnivores, and the modem species live in dense grass tussocks. Their evolutionary relationships are still a matter for conjecture but their anatomy suggests some affinities with either the Grylloblattodea (rock crawlers, ice crawlers) or Phasmatodea (stick insects). DNA studies may reveal molecular evidence which might help resolve the issue. The Arthropod Success Story The arthropod body plan comprises an external skeleton made of a remarkable horny substance called chitin, which has a high strength-to-weight ratio and is flexible and waterproof. The body plan has evolved independently at least four times. Modern systems of classification, therefore, no longer treat arthropods as a single group, "Arthropoda;" instead, they tend to divide them into different phyla with distinct origins. There are the terrestrial insects, myriapods, and their relatives (phylum Uniramia); the mainly terrestrial Chelicerata (spiders and relatives, and horseshoe crabs); and the chiefly marine crustaceans (crabs, shrimps, lobsters, and woodlice - phylum Crustacea). Smaller phyla include the terrestrial velvet worms (Onychophora), and the aquatic tongue worms (Pentastomida) and water bears (Tardigrada). Marine arthropods are not covered here. "Arthropodization" has enabled these animals to invade a wide range of habitats. Some of their adaptations are bizarre, ranging, in insects, from flies whose larvae live in hot springs or crude oil to a Malaysian moth that sucks the blood of animals; there are even fly larvae that live as internal parasites of barnacles. The list is endless, and ultra-specialization is a recurrent theme. On the other hand there are generalists too. Consider the physiological virtuosity of larvae of the little scuttlefly Megaselia scalaris , which, to date, have been reared from shoe polish, emulsion paint, human cadavers pickled in formalin, and the lungs of living people. If this volume has any linking theme, it is the arthropod success story. Our survey brings together a wealth of new information, hitherto burled in specialist journals and texts. An opening account of what it is to be an arthropod is followed by descriptions of all the major taxonomic groups, starting with the two superclasses of the phylum Uniramia, the myriapods (millipedes and centipedes) and the hexapods (mainly insects). Within the insects, each of the 28 different orders is treated separately, with a summary panel of salient facts, accompanied by a wider-ranging text outlining the major aspects of the group's natural history. An introduction to that other main group of terrestrial arthropods, the arachnids (class Arachnida of the phylum Chelicerata) is followed by sections on the mites and ticks, the spiders, and the scorpions and remaining subclasses. Throughout the book, boxed features, special feature spreads, and photo stories focus on topics of particular interest in behavior, morphology, ecology, or economic or medical importance. The illustrations in this encyclopedia do more than record the stunning variety of color, form, and lifestyle in terrestrial arthropods. The photographs, almost all by Premaphotos Wildlife, were taken in the wild, in locations all over the world. Here are revealed, in the subjects' natural habitat, details of arthropod life cycles and behavior, from the egg through larval stages and molting to adulthood, courtship, mating, feeding, and defense, flight, and death. Captions expand the scope of the text and identify species by family as well as by scientific name (if not given in the accompanying text or summary panel), and any common name. An important role is played by the artwork. Richard Lewington's color panels show the diversity and typical behavior of representatives of the major groups. The line drawings illustrate aspects of form and behavior covered in the text. The drawings in the Factfile panels are of species chosen to give some idea of the general appearance of many, if not all, members of the group in question. It is a pleasure to acknowledge the labors of an enthusiastic team of authors, all experts in their chosen fields. My thanks are also due to the dedicated publishing team at Andromeda Oxford Ltd., led by Dr Graham Bateman, Dr Peter Lewis and Chris Munday. I hope that together we have produced a volume that does justice to the swarming hordes of arthropods, which live out their intricate lives largely unseen and often unjustly reviled. Christopher O'Toole Hope Entomological Collections University Museum, Oxford Excerpted from Firefly Encyclopedia of Insects and Spiders All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
