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Books > Science & Mathematics > Biology, life sciences > Zoology & animal sciences > Invertebrates

Desert Arthropods: Life History Variations (Paperback, Softcover reprint of hardcover 1st ed. 2000): Fred Punzo Desert Arthropods: Life History Variations (Paperback, Softcover reprint of hardcover 1st ed. 2000)
Fred Punzo
R4,573 Discovery Miles 45 730 Ships in 10 - 15 working days

It is difficult for me to recollect a time when I was not fascinated with the very notion of a desert. Walt Disney's film, The Living Desert, which I initially saw when I was 8 years of age, provided me with my first glimpse of this wondrous yet seemingly ho stile environment. The images were hypnotic and captivating. I looked on in amazement at the promenade Cl deux of the male and female scorpions during courtship. Their rhythmic and coordinated movements as they grasped one another made them appear to glide in unis on over the surface of the sand, each individual totally absorbed with its partner. In the next minute the fern ale had suddenly and utterly transformed herself like some Jekyll and Hyde act, into an aggressive predator whose prior gregarious embrace was now a hold of death for the male. The indomitable desert grasshopper mouse, the ever sentient kit fox, the graceful shovel-nosed snake swimming in an endless sea of sand.

Carabid Beetles: Ecology and Evolution (Paperback, Softcover reprint of hardcover 1st ed. 1994): K. Desender, M. Dufrene, M.... Carabid Beetles: Ecology and Evolution (Paperback, Softcover reprint of hardcover 1st ed. 1994)
K. Desender, M. Dufrene, M. Loreau, M. L. Luff, J-P. Maelfait
R8,874 Discovery Miles 88 740 Ships in 10 - 15 working days

The Carabidae (including ground and tiger presented at the 8th European Carabidologists' beetles) form one of the largest families of in- Meeting - 2nd International Symposium of Cara- sects, with no less than an estimated 40,000 de- bidology, which took place at the Catholic Uni- scribed species, occurring in nearly any terrestrial versity of Louvain (U. c. L. ) in Louvain-Ia-Neuve and at the Royal Belgian Institute of Natural Sci- habitat on all continents (except Antarctica) as well as on most islands. This extreme diversity ences (R. B. I. N. S. ) in Brussels, Belgium, Septem- and distribution, along with the high abundance ber 1-4, 1992. The manuscripts were peer-re- of these beetles in a large variety of habitats has viewed prior to acceptance. resulted a considerable interest in many aspects of European Carabidologists' Meetings were their study, including systematics, biogeography, started in the late 1960s by ecologists, mostly ecology and evolution. A large number of ground from the Netherlands, Scandinavia and Germany, beetles are known as polyphagous predatory who were investigating various aspects of the bi- arthropods and therefore have been recognized ology of carabid beetles. Since that time the as beneficial insects in integrated pest manage- number of participants to that meeting as well as ment of cultures. This has stimulated ecological its content have expanded considerably.

Susswasserfauna von Mitteleuropa, Bd. 7/2-2 Chelicerata - Acari 2 (Paperback, Edition.): Reinhard Gerecke Susswasserfauna von Mitteleuropa, Bd. 7/2-2 Chelicerata - Acari 2 (Paperback, Edition.)
Reinhard Gerecke
R5,867 Discovery Miles 58 670 Ships in 10 - 15 working days

Chelicerata are a basically terrestrial group of invertebrates, including many clades whose representatives have never found an evolutionary way to aquatic live. An exception is made by some spiders and the highly diverse aquatic mites which in inland water habitats are represented by members of numerous different clades having evolved an aquatic or amphibious lifestyle along various evolutionary pathways. For the first time in limnofaunistic bibliography, the present taxonomic knowledge about these different groups of invertebrates is brought together in an overview for the Central-European fauna.

This second volume includes taxonomic keys and ecological information for the two species-rich superfamilies Hydryphantoidea and Lebertioidea of the freshwater mites (Hydrachnidia). A further volume in preparation will include the remaining two superfamilies, Hygrobatoidea and Arrenuroidea.

The chelicerata volumes of this series are a basic tool for all limnologists interested in diversity and ecology - in particular for biologists investigating the ecotones between ground- and surface water, between benthos and plankton, and between water and land.

Plant Resistance to Arthropods - Molecular and Conventional Approaches (Paperback, Softcover reprint of hardcover 1st ed.... Plant Resistance to Arthropods - Molecular and Conventional Approaches (Paperback, Softcover reprint of hardcover 1st ed. 2005)
C. Michael Smith
R1,646 Discovery Miles 16 460 Ships in 10 - 15 working days

This book synthesizes new information about the environmental advantages of plant resistance, transgenic resistance, the molecular bases of resistance, and the use of molecular markers to map resistance genes. Readers are presented in-depth descriptions of techniques to quantify resistance, factors affecting resistance expression, and the deployment of resistance genes. New information about gene-for-gene interactions between resistant plants and arthropod biotypes is discussed along with the recent examples of using arthropod resistant plants in integrated pest management systems.

Atlas of European Trichoptera - Atlas der Europaischen Koecherfliegen / Atlas des Trichopteres d'Europe (English, German,... Atlas of European Trichoptera - Atlas der Europaischen Koecherfliegen / Atlas des Trichopteres d'Europe (English, German, French, Paperback, Softcover reprint of hardcover 2nd ed. 2004)
Hans Malicky
R12,943 Discovery Miles 129 430 Ships in 10 - 15 working days

Caddis flies are important indicators of environmental quality in aquatic biotopes. This Atlas is the first book which enables the identification of the entire European caddis fly fauna since McLachlan s Revision and Synopsis of 1874-1880.

Identification of European caddis flies has proved difficult as a result of the widely scattered literature, and has therefore been a matter for specialists for more than hundred years.

This Second Edition of The Atlas of European Trichoptera contains over 1400 species which means an increase of 25% since the first edition of 1983.

Identification of specimens is one of the most difficult tasks in Zoology. This volume presents information which will enable the reader to develop his own opinions and will also help him reach decisions concerning the accuracy of his own results.

The identification of specimens is undertaken by comparing the detailed drawings of the most important characteristics of all species known in Europe, the Mediterranean countries north of the Sahara, the Canary islands, Madeira, the Azores islands and the adjacent eastern regions including the Arab Peninsula and Iran. The fauna of Turkistan and Siberia is partially included.

Explanations of the drawings are provided mainly by symbols which enable the use of this book independent of language. This concept has been proved successful in University courses.

The introductory chapters are in English, German and French. Should a reader not understand any of these languages, the translation of these few pages, including the pages of explanations, will provide sufficient understanding for the entire book."

Ticks and Tick-Borne Pathogens - Proceedings of the 4th International Conference on Ticks and Tick-Borne Pathogens The Banff... Ticks and Tick-Borne Pathogens - Proceedings of the 4th International Conference on Ticks and Tick-Borne Pathogens The Banff Centre Banff, Alberta, Canada 21-26 July 2002 (Paperback, Softcover reprint of the original 1st ed. 2003)
Frans Jongejan, W. Reuben Kaufman
R5,879 Discovery Miles 58 790 Ships in 10 - 15 working days

This volume contains the Proceedings of the 4th International Conference on Ticks and Tick-borne Pathogens (TTP-4), held in Banff, Alberta, Canada, from 21 to 26 July 2002. TTP-4 continues an important tradition established in 1992 at the first Conference in St. Paul, Minnesota, USA, and developed subsequently at the Kruger National Park, South Africa (1995) and the High Tatra Mountains, Slovakia (1999). The 31 papers published in this special issue are divided between six sessions, with a keynote address as an introduction. The first session, which deals with biosystematics, genomics and proteomics of ticks, contains the most recent world list of valid tick names. The papers deal with a broad range of tick-host-pathogen interactions, including remote sensing and mapping of ticks and tick-borne pathogens as well as practical aspects of tick control. It is recommended reading for anyone working on ticks and tick-borne pathogens, which are of increasing medical and veterinary importance worldwide.

Interrelationships Between Corals and Fisheries (Paperback): Ph.D., Stephen A. Bortone Interrelationships Between Corals and Fisheries (Paperback)
Ph.D., Stephen A. Bortone
R2,088 Discovery Miles 20 880 Ships in 12 - 17 working days

Interrelationships Between Corals and Fisheries is derived from a workshop held by the Gulf of Mexico Fishery Management Council in Tampa, Florida in May 2013, where world authorities came together to discuss the current problems in managing tropical fisheries and offered suggestions for future directions for both researchers and environmental resource managers. This book addresses current and emerging threats as well as challenges and opportunities for managing corals and associated fisheries. It provides an information baseline toward a better understanding of how corals and the consequences of coral condition influence fish populations, especially as they relate to management of those populations. The book contains content from presentations modified as a result of interactions and discussions with colleagues and peer reviews by global experts in corals and fisheries. Many chapters include additional materials not presented in the workshop. There are also papers that were not presented at the workshop but contribute to the central theme of the book. Topics covered include: Global decline in coral reefs and impacts on fishery yields Distribution and diversity in the Gulf of Mexico Implementation of Coral Habitat Areas of Particular Concern (CHAPCs) Deepwater coral/sponge habitats Coral populations on offshore platforms Mangrove connectivity for sustaining coral reef fisheries Restoring deepwater coral ecosystems and fisheries after the Deepwater Horizon oil spill Predictive mapping of coral reef fish Covering a range of subject matter, most of the chapters offer suggestions for future research on the interrelationships between corals and fisheries. In addition, the final chapter presents a summary on these interrelationships and discusses managing them for the future.

Echinodermata (Paperback, Softcover reprint of hardcover 1st ed. 2005): Valeria Matranga Echinodermata (Paperback, Softcover reprint of hardcover 1st ed. 2005)
Valeria Matranga
R4,550 Discovery Miles 45 500 Ships in 10 - 15 working days

Members of the phylum Echinodermata are among the most familiar marine invertebrates. Forms such as the sea star have become virtually a symbol of sea life. Used in ancient oriental medicine as a source of bioactive compounds, sea cucumbers, sea stars and sea urchins are now used for the extraction and purification of cytotoxic, haemolytic, antiviral, antifungal, antifouling, antimicrobial and even anti-tumoural activities. In addition, of the five extant classes, sea urchins and sea cucumbers are important economic resources for current fishery and aquaculture. Molecular and cell biological techniques described in this book are, on the one hand, indicative of the improvements made over the years and, on the other, stress the need of their further exploitation for the sustainable production of bioactive compounds and their application in biomedicine.

Herbivory of Leaf-Cutting Ants - A Case Study on Atta colombica in the Tropical Rainforest of Panama (Paperback, Softcover... Herbivory of Leaf-Cutting Ants - A Case Study on Atta colombica in the Tropical Rainforest of Panama (Paperback, Softcover reprint of hardcover 1st ed. 2003)
Rainer Wirth, Hubert Herz, Ronald J. Ryel, Wolfram Beyschlag, Bert Hoelldobler
R4,568 Discovery Miles 45 680 Ships in 10 - 15 working days

Plant-animal interactions have become a focus of ecological research, with the processes of herbivory being of special interest. This volume examines the interactions of leaf-cutting ants with the rainforest vegetation on Barro Colorado Islands in Central America. It is the synthesis of field research on multiple scales extending over a period of several years. This work can serve as a model study summarizing and extending knowledge about herbivorous insect-plant relationships, and the resulting consequences on structural and functional features of tropical ecosystems. The text is an invaluable reference for researchers and land managers working in the fields of plant-animal interactions, herbivory, community ecology and biodiversity.

Guide to Shieldbugs of the British Isles (Hardcover): Bernard Nau Guide to Shieldbugs of the British Isles (Hardcover)
Bernard Nau
R146 Discovery Miles 1 460 Ships in 12 - 17 working days
Low Temperature Biology of Insects (Hardcover): David L. Denlinger, Richard E Lee Jr Low Temperature Biology of Insects (Hardcover)
David L. Denlinger, Richard E Lee Jr
R3,497 Discovery Miles 34 970 Ships in 12 - 17 working days

Low temperature is a major environmental constraint impacting the geographic distribution and seasonal activity patterns of insects. Written for academic researchers in environmental physiology and entomology, this book explores the physiological and molecular mechanisms that enable insects to cope with a cold environment and places these findings into an evolutionary and ecological context. An introductory chapter provides a primer on insect cold tolerance and subsequent chapters in the first section discuss the organismal, cellular and molecular responses that allow insects to survive in the cold despite their, at best, limited ability to regulate their own body temperature. The second section, highlighting the evolutionary and macrophysiological responses to low temperature, is especially relevant for understanding the impact of global climate change on insect systems. A final section translates the knowledge gained from the rest of the book into practical applications including cryopreservation and the augmentation of pest management strategies.

Urban Insects and Arachnids - A Handbook of Urban Entomology (Hardcover): William H Robinson Urban Insects and Arachnids - A Handbook of Urban Entomology (Hardcover)
William H Robinson
R6,152 Discovery Miles 61 520 Ships in 12 - 17 working days

This account provides the first comprehensive coverage of the insect and other arthropod pests in the urban environment worldwide. Presented is a brief description, biology, and detailed information on the development, habits, and distribution of urban and public health pests. There are 570 illustrations to accompany some of the major pest species. The format is designed to serve as a ready-reference and to provide basic information on orders, families, and species. The species coverage is international and based on distribution in domestic and peridomestic habitats. The references are extensive and international, and cover key papers on species and groups. The introductory chapters overview the urban ecosystem and its key ecological components, and a review of the pests status and modern control strategies. The book will serve as a student textbook, professional training manual, and handbook for the pest control professionals, regulatory officials, and urban entomologists. It is organized alphabetically throughout.

Insect Diapause (Hardcover): David L. Denlinger Insect Diapause (Hardcover)
David L. Denlinger
R1,743 Discovery Miles 17 430 Ships in 12 - 17 working days

Our highly seasonal world restricts insect activity to brief portions of the year. This feature necessitates a sophisticated interpretation of seasonal changes and enactment of mechanisms for bringing development to a halt and then reinitiating it when the inimical season is past. The dormant state of diapause serves to bridge the unfavourable seasons, and its timing provides a powerful mechanism for synchronizing insect development. This book explores how seasonal signals are monitored and used by insects to enact specific molecular pathways that generate the diapause phenotype. The broad perspective offered here scales from the ecological to the molecular and thus provides a comprehensive view of this exciting and vibrant research field, offering insights on topics ranging from pest management, evolution, speciation, climate change and disease transmission, to human health, as well as analogies with other forms of invertebrate dormancy and mammalian hibernation.

Lifestyles and Feeding Biology (Hardcover): Martin Thiel, Les Watling Lifestyles and Feeding Biology (Hardcover)
Martin Thiel, Les Watling
R7,160 Discovery Miles 71 600 Ships in 10 - 15 working days

This second volume in the Natural History of the Crustacea series examines how crustaceans-the different body shapes and adaptations of which are described in volume 1-make a living in the wide range of environments they inhabit, and how they exploit food sources. The contributions in the volume give synthetic overviews of particular lifestyles and feeding mechanisms, and offer a fresh look at crustacean life styles through the technological tools that have been applied to recent crustacean research. These include SEM (scanning electron microscope) techniques, micro-optics, and long-term video recordings that have been used for a variety of behavioral studies. The audience will include not only crustacean biologists but evolutionary ecologists who want to understand the diversification of particular life styles, ecologists who follow the succession of communities, biogeochemists who estimate the role of crustaceans in geochemical fluxes, and biologists with a general interest in crustaceans.

Insects and Ecosystem Function (Paperback, 1st ed. 2004. 2nd printing 2007): W.W. Weisser, Evan Siemann Insects and Ecosystem Function (Paperback, 1st ed. 2004. 2nd printing 2007)
W.W. Weisser, Evan Siemann
R3,206 Discovery Miles 32 060 Ships in 10 - 15 working days

Insects are a dominant component of biodiversity in terrestrial ecosystems and play a key role in mediating the relationship between plants and ecosystem processes. This volume examines their effects on ecosystem functioning, focusing mainly, but not exclusively, on herbivorous insects. Renowned authors with extensive experience in the field of plant-insect interactions, contribute to the volume using examples from their own work.

Ecology and Applications of Benthic Foraminifera (Paperback): John W. Murray Ecology and Applications of Benthic Foraminifera (Paperback)
John W. Murray
R1,689 Discovery Miles 16 890 Ships in 12 - 17 working days

In this 2006 volume John Murray investigates the ecological processes that control the distribution, abundance and species diversity of benthic foraminifera in environments ranging from marsh to the deepest ocean. To interpret the fossil record it is necessary to have an understanding of the ecology of modern foraminifera and the processes operating after death leading to burial and fossilisation. This book presents the ecological background required to explain how fossil forms are used in dating rocks and reconstructing past environmental features including changes of sea level. It demonstrates how living foraminifera can be used to monitor modern-day environmental change. Ecology and Applications of Benthic Foraminifera presents a comprehensive and global coverage of the subject using all the available literature. It is supported by a website hosting a large database of additional ecological information (www.cambridge.org/0521828392) and will form an important reference for academic researchers and graduate students in Earth and Environmental Sciences.

Functional and Evolutionary Ecology of Fleas - A Model for Ecological Parasitology (Hardcover): Boris R Krasnov Functional and Evolutionary Ecology of Fleas - A Model for Ecological Parasitology (Hardcover)
Boris R Krasnov
R4,583 Discovery Miles 45 830 Ships in 12 - 17 working days

Fleas are one of the most interesting and fascinating taxa of ectoparasites. All species in this relatively small order are obligatory haematophagous (blood-feeding) parasites of higher vertebrates. This book examines how functional, ecological and evolutionary patterns and processes of host-parasite relationships are realized in this particular system. As such it provides an in-depth case study of a host-parasite system, demonstrating how fleas can be used as a model taxon for testing ecological and evolutionary hypotheses. The book moves from basic descriptive aspects, to functional issues and finally to evolutionary explanations. It extracts several general principles that apply equally well to other host-parasite systems, so it appeals not only to flea biologists but also to 'mainstream' parasitologists and ecologists.

Spiders of North America (Paperback): Sarah Rose Spiders of North America (Paperback)
Sarah Rose; Foreword by Eric R Eaton
R947 Discovery Miles 9 470 Ships in 9 - 15 working days

An accessible field guide to more than 500 of the most commonly found spider species in North America Of the more than 49,000 species of spider worldwide, some 4,000 are in North America. Spiders of North America explores more than 500 of the most common and interesting spiders found in this region of the world. This richly illustrated guide begins with an overview of spiders-what they are exactly, how they can be found, how they develop, and why they are important. The book features information on all the major spider guilds: sensing web weavers, sheet web weavers, orb web weavers, space web weavers, ambush hunters, ground active hunters, other active hunters, and spider hunters. Chapters contain accessible descriptions for identifying members of each spider family, including helpful tips for distinguishing members of similar families, and details at the genus and species levels. Stunning color photographs and informative distribution maps accompany the text. Useful descriptions for identification of each spider family Stunningly detailed macro and in-situ photographs Information on all the major spider guilds Handy distribution maps

Field Guide to the Ladybirds of Great Britain and Ireland (Paperback): Helen Roy, Peter Brown Field Guide to the Ladybirds of Great Britain and Ireland (Paperback)
Helen Roy, Peter Brown; Illustrated by Richard Lewington 1
R759 R708 Discovery Miles 7 080 Save R51 (7%) Ships in 12 - 17 working days

"A ground-breaking identification guide ... the perfect marriage of artistic excellence, deep knowledge and, dare I say it, of scientists' genuine affection." BRETT WESTWOOD This brand new illustrated field guide covers all 47 species of ladybird occurring in the British Isles in a handy and easy-to-use format. Twenty-seven species are colourful and conspicuous and easily recognised as ladybirds; the remaining species are more challenging, but the clear illustrations and up-to-date text in this guide will help to break down the identification barriers. A useful introduction provides an overview of ladybird ecology, tips on studying and recording, and suggested sites for finding ladybirds. The main part of the book comprises detailed species texts, covering field characters, food, habitats, suggested survey methods, ranges, conservation statuses and distribution trends. An illustrated at-a-glance identification guide and helpful pointers for differentiating similar-looking species are also included. With 102 colour photographs and 47 distribution maps, combined with Richard Lewington's peerless artwork, this is the definitive guide to one of our most cherished and charismatic insect groups.

Integrated Management of Insects in Stored Products (Paperback): Bhadriraju Subramanyam Integrated Management of Insects in Stored Products (Paperback)
Bhadriraju Subramanyam
R2,105 Discovery Miles 21 050 Ships in 12 - 17 working days

This work offers a comprehensive presentation of the identification, biology, ecology and sampling of insect pests in stored foods, and provides a balanced ciew of the biological, physical and chemical control methods used in pest management. It furnishes step-by-step procedures for creating individually tailored integrated pest management programmes. Every available method of control is covered.

Recent Freshwater Ostracods of the World - Crustacea, Ostracoda, Podocopida (Hardcover, 2012): Ivana Karanovic Recent Freshwater Ostracods of the World - Crustacea, Ostracoda, Podocopida (Hardcover, 2012)
Ivana Karanovic
R7,166 Discovery Miles 71 660 Ships in 12 - 17 working days

Their story began 500 million years ago, but we only started to get to know them in 1746, when Linne described the first ostracod species. Vividly portraying the freshwater ostracods, this comprehensive reference work gathers the knowledge gained during some 250 years, but which to date has remained scattered throughout the literature. It starts with an introduction to the class Ostracoda with a special focus on freshwater ostracods and highlights practical methods in their study. The systematic part includes an introduction to all families; identification keys for all subfamilies, genera and species; diagnoses for each subfamily and genus; and lists of synonyms and distribution of species. The text is richly illustrated with distribution maps, line drawings of key generic characteristics, and numerous SEM photographs. Serving as an excellent starting point for all further research on freshwater ostracods, it can be widely used not only by ostracodologists, but also by crustaceologists, evolutionists and ecologists.

Ants - The ultimate social insects (Hardcover): Richard Jones Ants - The ultimate social insects (Hardcover)
Richard Jones
R1,353 R1,064 Discovery Miles 10 640 Save R289 (21%) Ships in 12 - 17 working days

'Brilliant, Fantastic and Significant' - Dr George McGavin Ants are seemingly everywhere, and this familiarity has led to some contemptuous and less than helpful stereotypes. In this compelling insight into the natural and cultural history of ants, Richard Jones helps to unravel some of the myths and misunderstanding surrounding their remarkable behaviours. Ant aggregations in large (often mind-bogglingly huge) nests are a complex mix of genetics, chemistry, geography and higher social interaction. Their forage trails - usually to aphid colonies but occasionally into the larder - are maintained by a wondrous alchemy of molecular scents and markers. Their social colony structure confused natural philosophers of old and still taxes the modern biologist today. Beginning the book with a straightforward look at ant morphology, Jones then explores the ant species found in the British Isles and parts of nearby mainland Europe, their foraging, nesting, navigating and battle instincts, how ants interact with the landscape, their evolution, and their place in our understanding of how life on earth works. Alongside this, he explores the complex relationship between humans and ants, and how ants went from being the subject of fables and moral storytelling to become popular research tools. Drawing on up-to-date science and featuring striking colour photographs throughout, this book presents a convincing case for why ants are worth our greater recognition and respect.

Entomology (Hardcover, 3rd ed. 2005): Cedric Gillott Entomology (Hardcover, 3rd ed. 2005)
Cedric Gillott
R6,277 Discovery Miles 62 770 Ships in 10 - 15 working days

Gillott's thorough yet clear writing style continues to keep Entomology near the top of the class as a text for senior undergraduates, and for graduate students and professionals seeking an introduction to specific entomological topics. The author's long-held belief that an introductory entomology course should present a balanced treatment of the subject is reflected in the continued arrangement of the book in four sections: Evolution and Diversity, Anatomy and Physiology, Reproduction and Development, and Ecology. For the third edition, all chapters have been updated. This includes not only the addition of new information and concepts but also the reduction or exclusion of material no longer considered "mainstream", so as to keep the book at a reasonable size. Based on exciting discoveries made during the previous decade, the topics of insect evolutionary relationships, semiochemicals, gas exchange, immune responses (including those of parasites and parasitoids), flight, and the management of pests have received particular attention in the preparation of the third edition. Overall, more than 30 new or significantly revised figures have been incorporated.

Reproduction and Development in Echinodermata and Prochordata (Hardcover): T. J Pandian Reproduction and Development in Echinodermata and Prochordata (Hardcover)
T. J Pandian
R5,648 Discovery Miles 56 480 Ships in 12 - 17 working days

Echinoderms and prochordates occupy a key position in vertebrate evolution. The genomes of sea urchin share 70% homology with humans. Researches on cell cycle in sea urchin and phagocytosis in asteroids have fetched Nobel Prizes. In this context, this book assumes immense importance. Echinoderms are unique, as their symmetry is bilateral in larvae but pentamerous radial in adults. The latter has eliminated the development of an anterior head and bilateral appendages. Further, the obligate need to face the substratum for locomotion and acquisition of food has eliminated their planktonic and nektonic existence. Egg size, a decisive factor in recruitment, increases with decreasing depths up to 2,000-5,000 m in lecithotrophic asteroids and ophiuroids but remains constant in their planktotrophics. Smaller (< 18 mm) ophiuroids do not produce a lecithotrophic eggs but larger (> 110 mm) asteroids generate planktotrophic eggs only. Publications on sex ratio of echinoderms indicate the genetic determination of sex at fertilization but those on hybridization, karyotype and ploidy induction do not provide evidence for heterogametism. But the herbivorous echinoids and larvacea with their gonads harboring both germ cells and Nutritive Phagocytes (NPs) have economized the transportation and hormonal costs on gonadal function. Despite the amazing potential just 2 and 3% of echinoderms undergo clonal reproduction and regeneration, respectively. Fission is triggered, when adequate reserve nutrients are accumulated. It is the most prevalent mode of clonal reproduction in holothuroids, asteroids and ophiuroids. However, budding is a more prevalent mode of clonal reproduction in colonial hemichordates and urochordates. In echinoderms, fission and budding eliminate each other. Similarly, autoregulation of early development eliminates clonal reproduction in echinoids and solitary urochordates. In pterobranchs, thaliaceans and ascidians, the repeated and rapid budding leads to colonial formation. Coloniality imposes reductions in species number and body size, generation time and life span, gonad number and fecundity as well as switching from gonochorism to simultaneous hermaphorditism and oviparity to ovoviviparity/viviparity.

Praying Mantis vs. Black Widow Spider (Paperback): Kieran Downs Praying Mantis vs. Black Widow Spider (Paperback)
Kieran Downs
R261 Discovery Miles 2 610 Ships in 10 - 15 working days
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