This chapter provides an overview of the Lophotrochozoa and the phylum Mollusca. The Mollusca, Nemertea, Annelida, and the three lophophorate phyla comprise the clade Lophotrochozoa in the form of the so-called small shelly fossils. Molluscs comprise the second largest phylum of animals (after arthropods) and include some of the best-known invertebrates. The chapter then details the body plan and the very long and convoluted taxonomic history and classification of molluscs. Despite the enormous diversity, all molluscs share a suite of defining characteristics that include bilateral symmetry, reduced coelom, visceral mass, body covered by the mantle, ctenidia, radula and spiral cleavage.
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Chapter
Introduction to the Lophotrochozoa, and the Phylum Mollusca
Book
F. Harvey Pough, William E. Bemis, Betty Mcguire, and Christine M. Janis
Vertebrate Life explores how the anatomy, physiology, ecology, and behaviour of animals interact to produce organisms that function effectively in their environments, and how lineages of organisms change through evolutionary time. It looks at the evolution, diversity, and classification of vertebrates. It considers chondrichthyes, osteichthyes as well as teteapods. Ectothermy is examined as an example of a low-energy approach to life. Other vertebrates considered are turtles, lepidosaurs, crocodylians, and extant birds and mammals.
Chapter
Diversity, Classification, and Evolution of Vertebrates
This chapter explores the diversity, classification, and evolution of vertebrates. It highlights how evolution is central to biology since its overarching principles allow further understanding of how living organisms operate and organize their diversity. Phylogenetic systematics produces branching evolutionary diagrams or phylogenetic trees which show changes in characteristics. The chapter then covers the genetic mechanisms and environmental events that have shaped the evolution and biology of vertebrates. It looks into Earth's history in relation to the evolution of vertebrates and Earth's pattern of fragmentation and coalescence which isolated and renewed contacts of major groups of vertebrates, and which then produced the biogeographic distributions of vertebrates.
Chapter
The Diversity of Benthic Marine Invertebrates
This chapter explores the diversity of marine benthic invertebrates. It focuses on the Cambrian explosion of animal life about 540 million years ago, which resulted in some evolutionary changes that allowed for the development of morphological and behavioral complexity. Benthic invertebrates with radial symmetry have a center of symmetry, and bilateral symmetry is often associated with directional movement and anterior sense organs. Complexity and different degrees of evolutionary transformation can be found in terms of symmetry and organ types. The chapter considers the characteristics and structure of various invertebrates, such as Cnidaria, Platyhelminthes, Nemertea, and Protists. It also looks into mollusks, arthropods, echinodermata, and urochordata.
Chapter
The Tree of Life
This chapter focuses on the aspect of evolution represented by a phylogenetic tree. It
explains that phylogeny is the study of the history of cladogenetic events and explains how
species or other taxa successfully arose from a common ancestor. The diversity of life has
evolved over so long a time and this has involved hybridization and horizontal gene
transfer. The chapter also notes how phylogenetic methods can be used to explain the history
not only of species, but also of DNA sequences, gene families, tumors and other cell
lineages, and cultural traits. It explains the notion of mosaic evolution wherein different
characters commonly evolve at different rates.
Chapter
The Diversity, Organization, and Classification of Life
This chapter discusses the diversity, organisation, and classification of life. It talks about the natural human tendency of grouping and identifying things with appropriate labels. Taxonomy is the term used for the naming and grouping of biological organisms. The resulting collection of names forms a biological nomenclature. The chapter discusses the traditional, Linnaean taxonomic approach that categorizes all living organisms into the broad categories of Plantae or Animalia and the systematic interpretation of organismal relationships. It then looks into the pitfalls of taxonomic interpretations, for example, fixed classification and misleading names.
Chapter
The Diversity, Organization, and Classification of Life
This chapter discusses the diversity, organisation, and classification of life. It talks about the natural human tendency of grouping and identifying things with appropriate labels. Taxonomy is the term used for the naming and grouping of biological organisms. The resulting collection of names forms a biological nomenclature. The chapter discusses the traditional, Linnaean taxonomic approach that categorizes all living organisms into the broad categories of Plantae or Animalia and the systematic interpretation of organismal relationships. It then looks into the pitfalls of taxonomic interpretations, for example, fixed classification and misleading names.
Chapter
Why are most species small?
This chapter explores body size and diversity. An organism's body size places severe constraints on its fundamental architecture and physiology, and therefore the way it obtains energy and resources from the environment, assimilates energy into body tissue, and uses it for growth and reproduction. The frequency distribution (histogram) of body sizes for large groups of species is often right-skewed on a logarithmic scale. This indicates a strong bias in species numbers towards species of smaller size. But it also requires us to explain the low species richness at the very smallest sizes. There are many hypotheses for this uneven distribution of body size, some focusing on the relative lack of small species, and others on the low numbers of both very small and very large species.
Chapter
Why are there so many kinds of beetles?
This chapter studies beetle diversity. Beetles are the largest order of animals on earth; their diversity eclipses other insect orders, even their nearest relatives. Why are beetles, of all groups, so diverse? Is there something about their biology or ecology that has promoted diversification, do they have a longer evolutionary history than other groups, or is the great diversity of beetles simply the outcome of random diversification processes? By investigating some of the proposed explanations for the great diversity of beetles, we can get to grips with the basic logic of setting up comparative analyses to discover why diversity is so unevenly distributed among clades. Exploring beetle diversity is also a good way to become familiar with the ways that evidence from phylogenetics, biogeography, and palaeontology can be used to describe patterns and test hypotheses for variation in diversity.
Chapter
Introduction
This introductory chapter provides an overview of the diversity of extant invertebrates living on Earth. It explains how classifications reflect how people view the evolutionary history of life, which consists of evolutionary relationships and phylogenetic history. Classifications are lists of species, ranked in a subordinated fashion that reflects their evolutionary relationships and phylogenetic history. Moreover, marine, freshwater, and terrestrial environments present different kinds of challenges for animals, especially in terms of water balance, excretion, reproduction, support, and locomotion. Significant changes in animal phylogeny primarily revolve around the rapidly expanding field of molecular phylogenetics, new paleontological work and new ultrastructural and embryological studies.
Chapter
Turtles
This chapter notes the unique structure of turtles. The unique body form of turtles makes them immediately recognizable, but their anatomical rearrangements have obscured morphological characteristics which are used to determine evolutionary affinities among other vertebrates. The shells of different turtle species reveal their habitat and lifestyle of living in terrestrial, freshwater and marine environments. The chapter discusses the form, diversity, social behavior, reproduction, and migration of turtles. It then acknowledges how more than half of the extant species of turtles are facing extinction as they are not safe from humans even though they are relatively safe from natural predators.
Chapter
Therians
This chapter tackles the evolutionary history of Theria and its two clades, Marsupalia and Eutheria. Therians are viviparous amniotes which give birth to young after a period of internal gestation. Although most therians are terrestrial, there are also therians with burrowing, aquatic, and flying forms. Thus, the evolution of these different ways of life led to corresponding diversity in anatomy, body size, and ecology, as well as many striking cases of convergent evolution. The chapter considers the diversity of Metatheria and Eutheria in relation to the key elements of therian reproductive biology and specializations for feeding and locomotion. It notes how mammals front extinction risk at the hands of humans, which includes habitat loss and the introduction of alien species.
Chapter
Benthic Microorganisms, Seaweeds, and Sea Grasses
This chapter discusses the diversity of microorganisms, algae, and plants that live on the seabed. It primarily focuses on benthic microorganisms, seaweeds, and sea grasses. All living organisms can be divided among basic domains based on DNA sequence relationships. Thus, according to Carl Worse and his colleague's data from DNA sequencing of ribosomal DNA genes: the three major divisions of life were Archaea, Bacteria, and Eukarya. The chapter also considers the function and characteristics of bacteria, which are known to be crucial in the process of decomposition. It discusses the features of cyanobacteria, diatoms, fungi, seaweeds, chlorophyta, and sea grasses.
Chapter
Phylogeny: The Unity and Diversity of Life
This chapter describes the concept of phylogeny in relation to the unity and diversity of
life. It explains that phylogenetic relationships among species are estimated from
similarities and differences, but estimation could be difficult due to factors like
homoplasy and rapid diversification. Parsimony is the simplest method to estimate
phylogenies from DNA sequences, but likelihood and Bayesian inference also have their
respective advantages as well. The chapter looks into the hypothesis of adaptation via
natural selection through the comparative method. It also details how modern systematics
based the classification of organisms on phylogeny. Additionally, classification reflects
evolutionary history and a great deal of information about the species.
Chapter
Microbial Diversity
This chapter explores the notion of microbial diversity. In response to the huge number of living organisms across the planet, the idea of creating taxonomies was developed for the biological classification and grouping together of organisms that share properties. The chapter tackles the main ways of gathering information to determine the classification of an organism: classification taxonomy and molecular taxonomy. The habitats of soil, freshwater, and seawater showcase the incredible diversity of microbial life. The chapter also considers how technologies like sequencing and metagenomics unveiled the expanse of unculturable microbes. It provides an overview of the diversity of bacteria, Archaea, fungi, and protists by detailing their characteristics and features.
Chapter
Body Plans
This chapter tackles the growth and forms of living organisms which depend on physical and mathematical imperatives and are shaped by the pressures of evolution. It notes that the diversity of organisms is due to differences in habitats, sizes, and shapes. Multicellular organisms develop by the replication and differentiation of cells. Furthermore, cells vary in their capacity for differentiation between organisms and at different stages of life. While plant structures emerge at fixed points, complex animals have originated from a bilaterian ancestor evolved in two distinct branches according to whether the blastopore forms the mouth or anus. The chapter illustrates that organisms representing virtually all forms of eukaryotic life develop hard body materials.
Book
Jon Scott, Gus Cameron, Anne Goodenough, Dawn Hawkins, Jenny Koenig, Martin Luck, Despo Papachristodoulou, Alison Snape, Kay Yeoman, and Mark Goodwin
Biological Science: Exploring the Science of Life spans the full scale of biological science — from molecule to ecosystem. The first part of the text looks at life and its exploration. Topics covered in this section include exploring the science of life, the emergence of life on earth, defining life, evolutionary processes, and the diversity and organisation of life. Here, classification of life is also dealt with. The next section moves on to quantitative toolkits. Here, the text showcases nine toolkits which look at understanding data, size and scale, describing data, ratio and proportion, understanding samples, designing experiments, assessing patterns, formulae and equations, and rates of changes. Thereafter there are five modules. The first module is about life at the molecular level. Topics here include genetics, genomes, proteins, metabolism, and molecular tools. The second module looks at life at the cellular level. Here the text examines cell division, microbial diversity, microbes in life, and viruses. Module 3 is about the human organism and looks in detail at tissues, organs, and systems. The fourth module covers organismal diversity and describes structure, adaptation, and survival. The text finishes with a fifth module which looks at organism in their environments. Here, the chapters turn to ecology, evolution, genes, populations, communities, and ecosystems.
Chapter
Microbial Diversity
This chapter explores the notion of microbial diversity. In response to the huge number of living organisms across the planet, the idea of creating taxonomies was developed for the biological classification and grouping together of organisms that share properties. The chapter tackles the main ways of gathering information to determine the classification of an organism: classification taxonomy and molecular taxonomy. The habitats of soil, freshwater, and seawater showcase the incredible diversity of microbial life. The chapter also considers how technologies like sequencing and metagenomics unveiled the expanse of unculturable microbes. It provides an overview of the diversity of bacteria, Archaea, fungi, and protists by detailing their characteristics and features.
Chapter
How did evolution get started?
This chapter discusses how evolution started on earth. For evolution to occur, there must be a population of replicators able to copy themselves with near-perfect accuracy, with occasional variations that provide the potential for natural selection to improve copying ability. The capacity for heritable information can be increased by combining previously independent replicators into coordinated systems that rely on each other for replication. The major transitions in evolution are macroevolutionary events that led to increases in informational capacity, permitting the evolution of diversity and complexity over time. The chapter then looks at the use of experiments and models in considering the origin of life. While models and experiments are general tools employed in many different scientific fields, there is another method for testing ideas that is particular to evolution. The evolutionary comparative method uses comparisons between the end products of evolution to make inferences about evolutionary process and history.
Book
Jon Scott, Gus Cameron, Anne Goodenough, Dawn Hawkins, Jenny Koenig, Martin Luck, Despo Papachristodoulou, Alison Snape, Kay Yeoman, and Mark Goodwin
Biological Science: Exploring the Science of Life spans the full scale of biological science — from molecule to ecosystem. The first part of the text looks at life and its exploration. Topics covered in this section include exploring the science of life, the emergence of life on earth, defining life, evolutionary processes, and the diversity and organisation of life. Here, classification of life is also dealt with. The next section moves on to quantitative toolkits. Here, the text showcases nine toolkits which look at understanding data, size and scale, describing data, ratio and proportion, understanding samples, designing experiments, assessing patterns, formulae and equations, and rates of changes. Thereafter there are five modules. The first module is about life at the molecular level. Topics here include genetics, genomes, proteins, metabolism, and molecular tools. The second module looks at life at the cellular level. Here the text examines cell division, microbial diversity, microbes in life, and viruses. Module 3 is about the human organism and looks in detail at tissues, organs, and systems. The fourth module covers organismal diversity and describes structure, adaptation, and survival. The text finishes with a fifth module which looks at organism in their environments. Here, the chapters turn to ecology, evolution, genes, populations, communities, and ecosystems.
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