This book is the second volume in a series of 4 volumes in the Handbook of Zoology series treating morphology, anatomy, reproduction, development, ecology, phylogeny, systematics and taxonomy of polychaetous Annelida. In this volume a comprehensive review of a few more derived higher taxa within Sedentaria are given, namely Sabellida, Opheliida/Capitellida as well as Hrabeiellidae. The former comprise annelids possessing a body divided into two more or less distinct regions or tagmata called thorax and abdomen. Here two groups of families are united, the spioniform and sabelliform polychaetes. Especially Spionidae and Sabellidae are speciose families within this group and represent two of the largest annelid families. These animals live in various types of burrows or tubes and all possess so-called feeding palps. In one group these appendages are differentiated as grooved feeding palps, whereas in the other they may form highly elaborated circular tentacular crowns comprising a number of radioles mostly giving off numerous filamentous pinnulae. Often additionally colourful, the latter are also received the common names "feather-duster worms", "flowers of the sea", "Christmas-tree worms". Opheliida/Capitellida including five families of truly worm-like annelids without appendages represents the contrary. Their members burrow in soft bottom substrates and may be classified as non-selective deposit feeders. Molecular phylogenetic analyses have shown that Echiura or spoon worms, formerly regarded to represent a separate phylum, are members of this group. Last not least Hrabeiellidae is one out of only two families of oligochaete-like terrestrial polychaetes and for this reason received strong scientific interest.

This volume of the Handbook of Zoology summarizes "small" groups of animals across the animal kingdom. Dicyemida and Orthonectida are enigmatic parasites, formerly united as "Mesozoa" and their position among the multicellular animals is still not known with certainty. Placozoa are small, flat marine animals which provide important information on metazoan evolution. Comb jellies (Ctenophora) are esthetically fascinating animals which cause considerable discussion about their phylogenetic position. Seisonida are closely related to rotifers and acanthocephalans. Cycliophora were discovered and described as one of the last higher taxa and surprise by their complex life cycle. Kamptozoa (= Entoprocta) are small sessile animals in the sea and sometimes also in freshwater. Arrow worms (Chaetognatha) play an important role as predators in the plankton, but they also include benthic forms. Pterobranchia and acorn worms (Enteropneusta) belong to the deuterostomia and are related to echinoderms. In particular enteropneusts play an important role in understanding deuterostome evolution. These chapters provide up to date reviews of these exiting groups with reference to the important literature and therefore serves as an important source of information.

This volume of the series Handbook of Zoology deals with the anatomy of the gastrointestinal digestive tract - stomach, small intestine, caecum and colon - in all eutherian orders and suborders. It presents compilations of anatomical studies, as well as an extensive list of references, which makes widely dispersed literature accessible. Introductory sections to orders and suborders give notice to biology, taxonomy, biogeography and food of the respective taxon. It is a characteristic of this book that different sections of the post-oesophageal tract are discussed separately from each other. Informations on form and function of organs of digestion in eutherians are discussed under comparative-anatomical aspects. The variability and diversity of anatomical structures represents the basis of functional differentiations.

This section of the Handbook of Zoology is intended as a comprehensive and exhaustive account of the biology of the taxa Gastrotricha, Nematoda, Nematomorpha, Priapulida, Kinorhyncha, Loricifera, Gnathostomulida, Micrognathozoa, Rotifera, Seisonida and Acanthocephala, covering all relevant topics such as morphology, ecology, phylogeny and diversity. The series is intended to be a detailed and up-to-date account of these taxa. As was the case with the first edition, the Handbook is intended to serve as a reliable resource for decades. Many of the taxa of this volume are comparatively unknown to many biologists, despite their diversity and importance for example in meiofaunal communities (Gastrotricha, Rotifera, Gnathostomulida), their fascinating recent discoveries (Loricifera and Micrognathozoa), their importance as parasites (many nematodes, Nematomorpha, Acanthocephala) and their importance for evolutionary questions (e.g. Priapulida, Gastrotricha). The groups covered range from those poor in species (such as Micrognathozoa with 2 known species) to the species-rich and diverse Nematoda and their ca. 20.000 described species. While each taxon is covered by one chapter, nematodes are treated in several chapters dedicated to their structural, taxonomic and ecological diversity.

Covering 100 years of zoological research, the Handbook of Zoology represents a vast store of knowledge. Handbook of Zoology provides an in-depth treatment of the entire animal kingdom covering both invertebrates and vertebrates. It publishes comprehensive overviews on animal systematics and morphology and covers extensively further aspects like physiology, behavior, ecology and applied zoological research. Although our knowledge regarding many taxonomic groups has grown enormously over the last decades, it is still the objective of the Handbook of Zoology to be comprehensive in the sense that text and references together provide a solid basis for further research. Editors and authors seek a balance between describing species richness and diversity, explaining the importance of certain groups in a phylogenetic context and presenting a review of available knowledge and up-to-date references. New contributions to the series present the combined effort of an international team of editors and authors, entirely published in English and tailored to the needs of the international scientific community. Upcoming volumes and projects in progress include volumes on Annelida (Volumes 1-3), Bryozoa, Mammalia, Miscellaneous Invertebrates, Nannomecoptera, Neomecoptera and Strepsiptera and are followed later by fishes, reptiles and further volumes on mammals. Background The renowned German reference work Handbook of Zoology was founded in the 1920's by Professor Willi Kukenthal in Berlin and treated the complete animal kingdom from single cell organisms to mammals in eight thematic volumes: Volume I Protozoa, Porifera, Colenteratea, Mesozoa (1925); Volume II Vermes (1933/34); Volume III Arthropoda ex. Insecta (1927/1932); Volume IV Arthropoda: Insecta; Volume V Solenogastres, Mollusca, Echinoderma (1925); Volume VI Pisces / Amphibia (1930); Volume VII Reptilia / Aves (1931); Volume VIII Mammalia. The Volumes IV Arthropoda: Insecta and VII Mammalia continued publication into the present with the most recent contributions in English language. Adapting to the accelerating speed of scientific discovery in the past decades the Handbook of Zoology entered a next phase in 2010. In the new edition of the Handbook of Zoology, the original eight thematic volumes gave way for smaller and more flexible groupings that reflect the current state of phylogenetic knowledge. All subsequent volumes were published in print as well as e-book format. The Handbook of Zoology is additionally offered as a database, the Handbook of Zoology Online, which can easily be searched and rapidly updated. Original Handbook material (ca. 28 000 pages) has been reordered along taxonomic (instead of bibliographical) categories and forms the historical basis of this Online Reference Work. As a living Online Reference, the content is continuously updated and new content added. The material can be accessed through taxonomic and subject categories as well as free text, with a diversity of linking and search options. Faster publication times through online-first publication, reference- and cross-linking, and make the Handbook of Zoology highly attractive to both authors and users.

This book is the first in a series of 4 volumes in the Handbook of Zoology series about morphology, anatomy, reproduction, development, ecology, phylogeny and systematics of Annelida. This first volume covers members of the so-called basal radiation and the first part of Sedentaria. It is supplemented by chapters on the history of annelid research, their fossil record, and an introduction to the phylogeny of annelids and their position in the tree of life. In the latter chapter the history of their systematic is reviewed giving an almost complete picture of systematic-scientific progress especially in the past years which changed our view on annelid phylogeny dramatically. The most basal annelids, lately united as Palaeoannelida, represent two families of aberrant polychaetes formerly often suggested to be highly derived which now give us a fresh look on how the ancestral annelid may have looked like. These lack certain key characters such as nuchal organs and possess rather simple nervous systems which now likely represent primitive character states. In this basal radiation the first taxon of apparently unsegmented and achaetigerous animals is positioned, the Sipuncula. Most likely another group of platyhelminth-like and unsegmented and even chaeta-lees annelids, Lobatocerebridae falls into this basal radiation. The section of Sedentaria starts with Orbiniida, a taxon characterized by elongated, thread-like worms which do not have anterior appendages like palps and comprises several families representing members of the Meiofauna. These minute worms often inhabiting the interstitial spaces in marine sands are suggested to have evolved by progenesis. The second higher taxon is represented by Cirratuliformia comprising nine families of typical sedentary polychaetes each of which showing a remarkable variation of the annelid body plan. Members of this taxon usually exhibit many annelid characters but certain also lack the most typical prostomial appendages, the palps.