Multicellular Animals

No one can ever have secure knowledge about the gods and creatures, and should anyone hit by chance upon the right thing, he will not know it for sure; that is why everything that we believe to be true is "opinion". XENOPHANES around 500 B.C. (According to ROD 1988, p.85) The goal of phylogenetic systematics (cladistics) is to discover the kinship relations between all organisms on earth and to translate the order we perceive in Nature into an equivalent man-made system. Although the goal is easily formulated, the path is thorny, and the results achieved continue to be imperfect. This is the fate of any science that bases its propositions on the interpretation of histor ical evidence. The diversity found in the millions of species originated as a result of the continuous splitting of biopopulations through time. Combined with this was the emergence of hierarchically linked des cent communities of species. We call the process of origin of descent communities phylogenesis. We do not know, however, the exact course of phylogenesis - we can only formulate hypotheses. The historical evidence at hand consists of the feature patterns of extant species and of extinct species with their combination of original and derived traits which are the result of evolution.

The system of multicellular animals presented here is an alternative to the traditional classification system. In a new approach to the phylogenetic order, this book strives for an objective systematization of the metazoa, seeking a new path in the field of academic research and teaching.

Volume III

Volume III

Concepts of Biology is designed for the single-semester introduction to biology course for non-science majors, which for many students is their only college-level science course. As such, this course represents an important opportunity for students to develop the necessary knowledge, tools, and skills to make informed decisions as they continue with their lives. Rather than being mired down with facts and vocabulary, the typical non-science major student needs information presented in a way that is easy to read and understand. Even more importantly, the content should be meaningful. Students do much better when they understand why biology is relevant to their everyday lives. For these reasons, Concepts of Biology is grounded on an evolutionary basis and includes exciting features that highlight careers in the biological sciences and everyday applications of the concepts at hand.We also strive to show the interconnectedness of topics within this extremely broad discipline. In order to meet the needs of today's instructors and students, we maintain the overall organization and coverage found in most syllabi for this course. A strength of Concepts of Biology is that instructors can customize the book, adapting it to the approach that works best in their classroom. Concepts of Biology also includes an innovative art program that incorporates critical thinking and clicker questions to help students understand--and apply--key concepts.

Among the most important innovations in the history of life is the transition from single-celled organisms to more complex, multicellular organisms. Multicellularity has evolved repeatedly across the tree of life, resulting in the evolution of new kinds of organisms that collectively constitute a significant portion of Earth’s biodiversity and have transformed the biosphere. This volume examines the origins and subsequent evolution of multicellularity, reviewing the types of multicellular groups that exist, their evolutionary relationships, the processes that led to their evolution, and the conceptual frameworks in which their evolution is understood. This important volume is intended to serve as a jumping-off point, stimulating further research by summarizing the topics that students and researchers of the evolution of multicellularity should be familiar with, and highlighting future research directions for the field.