Reproduction and Development in Annelida

T. J. Pandian

• Publisher: CRC Press
• Year: 2019
• Print ISBN: 9780367187453
• eBook ISBN: 9780429582585
• Edition: 1
• Topic: Medicine
• Subtopic: Veterinary Medicine

This book is a concise informative elucidation of all aspects of reproduction and development in annelids covering from arenicola to tubifex. Annelids flourish between 4, 900 m depth to 2, 000 m altitude; some of them occur in unusual habitats like hydrothermal vents and subterranean aquatic system (stigobionts). A few have no gut and acquire adequate nutrients through osmotrophism and/or engaging symbiotic microbes. In the absence of exoskeleton to escape predation, the 17, 000 speciose annelids have explored bewildering modes of reproduction; not surprisingly, 42–47% of them are brooders. With 13, 000 species, polychaetes are gonochores but some 207 species of them are hermaphrodites. Clitellates are all hermaphrodites; of them, 76 species are parthenogens, of which 56 are earthworms.

Regenerative potency of annelids ranges from an organ to an entire worm from a single 'seminal' segment. The head, tail and both together can be regenerated 21, 42 and 20 times, respectively. However, the potency is limited to ~1% of polychaetes and < 2% of oligochaetes. In oligochaetes, the chloragogue temporally separates regeneration and reproduction but sedentary polychaetes undertake them together at the reduced reproductive output. Only 79 polychaete and 111 oligochaete species have the potency for clonal reproduction. Within families, the potency ranges from 2% in spionids to 54% in naidids. Epitoky, a spectacular and unique phenomenon, involves the transformation from benthic to meroplanktonic reproductive morphism. It occurs in 106 errant polychaete species. The larger glycerides, nereidids and eunicids use muscular energy to climb < 50 m vertical distance. But the small phyllodocids and cteniodrilids may reduce buoyancy to climb 1, 000–4, 000 m vertical distance.

Heterogamatic sex determination is reported to occur only in six polychaete species, although karyotype is known for 83 annelid species. In temperate polychaetes, a dozen neuroendocrines, arising mostly from the 'brain' regulates reproductive cycle. A complete chapter devoted to vermiculture, (i) recognizes the fast-growing candidate species, (ii) distinguishes 'layers' from 'brooders', (iii) indicates that the harvest of oligochaetes may reduce the input of nitrogenous fertilizer in the ricefield, and (iv) explores the scope for increasing wealth from waste.

Contents

Preface to the Series

Preface

Acknowledgment

1 Introduction

1.1 Annelidan Science

1.2 Species and Structural Diversity

1.3 Geographic Distribution

1.4 Gutless Oligochaetes

1.5 Hydrothermal Vents and Cold Seeps

1.6 Energy Budget

1.6.1 Osmotrophism

1.6.2 Anaerobiosis

1.7 Life Span and Generation Time

1.8 Gametogenesis

1.9 Reproductive Modes and Dispersal

1.10 Fertilization Site and Success

1.11 Annelidan Larvae

1.12 Defense and Parental Care

1.13 Metamorphosis and Settlement

2 Sexual Reproduction

Introduction

2.1 Reproductive Systems

2.2 Gonochorism

2.2.1 Sex Ratio

2.2.2 Ovary Somatic Index

2.3 Hermaphroditism

2.4 Parthenogenesis

2.4.1 Parthenogenic Types

2.4.2 Parthenogenic Levels

2.4.3 Ploidy Levels

2.5 Fecundity

2.5.1 Sexuality

2.5.2 Oogenic Anlage

2.5.3 Egg Size

2.5.4 Body Size

2.6 Poecilogony and Dispersal

2.7 Mating Systems

2.7.1 Simultaneous Hermaphrodites

2.7.2 Sequential Hermaphrodites

2.7.3 Labile Gonochorics

3 Regeneration

Introduction

3.1 Regeneration and Reproduction

3.2 Incidence and Prevalence

3.3 Regenerative Process

3.3.1 Wound-healing

3.3.2 Cell Migration

3.3.3 Blastema and Differentiation

3.3.4 Segmentation and Reorganization

3.4 Anterior vs Posterior

4 Asexual Reproduction

Introduction

4.1 Obligate Cloners?

4.2 Incidence and Prevalence

4.3 Observations and Characteristics

4.4 Architomy

4.5 Naidu’s Monograph

4.6 Paratomy

4.7 Restoration of Sexual Reproduction

4.8 Clonal Stem Cells

5 Epitoky

Introduction

5.1 Types and Characteristics

5.2 Epigamy

5.3 Schizogamy

5.4 Vertical Migration

5.5 Swarming Phenomenon

5.6 Pheromones and Spawning

6 Sex Determination

Introduction

6.1 Karyotype and Heterogamety

6.2 Gametic Compatibility

6.3 Sex Ratio and Variations

7 Sex Differentiation

Introduction

7.1 Endocrine Regulation

7.1.1 Nereidids

7.1.2 Nephtyids

7.1.3 Phyllodocids

7.1.4 Arenicolids

7.2 Differentiation and Lability

7.2.1 Dorvilleids

7.2.2 Syllids

7.3 Pollutants and Reproduction

7.4 Vectors and Borers

8 Vermiculture

Introduction

8.1 Characteristics and Features

8.2 Candidate Species

8.2.1 Growth

8.2.2 Reproduction

8.2.3 Polyploids and Parthenogens

9 Summary and New Findings

10 References

Author Index

Species Index

Subject Index

Author’s Biography

Preface to the Series

Invertebrates surpass vertebrates not only in species number but also in diversity of sexuality, modes of reproduction and development. Yet, we know much less of them than we know of vertebrates. During the 1950s, the multi volume series by L.E. Hyman accumulated bits and pieces of information on reproduction and development of aquatic invertebrates. Through a few volumes published during the 1960s, A.C. Giese and A.S. Pearse provided a shape to the subject of Aquatic Invertebrate Reproduction. Approaching from the angle of structure and function in their multi-volume series on Reproductive Biology of Invertebrates during the 1990s, K.G. Adiyodi and R.G. Adiyodi elevated the subject to a visible and recognizable status.

Reproduction is central to all biological events. The life cycle of most aquatic invertebrates involves one or more larval stage(s). Hence, an account on reproduction without considering development shall remain incomplete. With the passage of time, publications are pouring through a large number of newly established journals on invertebrate reproduction and development. The time is ripe to update the subject. This treatise series proposes to (i) update and comprehensively elucidate the subject in the context of cytogenetics and molecular biology, (ii) view modes of reproduction in relation to Embryonic Stem Cells (ESCs) and Primordial Germ Cells (PGCs) and (iii) consider cysts and vectors as biological resources.

Hence, the first chapter on Reproduction and Development of Crustacea opens with a survey of sexuality and modes of reproduction in aquatic invertebrates and bridges the gaps between zoological and stem cell research. With capacity for no or slow motility, the aquatic invertebrates have opted for hermaphroditism or parthenogenesis/polyembryony. In many of them, asexual reproduction is interspersed within sexual reproductive cycle. Acoelomates and eucoelomates have retained ESCs and reproduce asexually also. However, pseudocoelomates and haemocoelomates seem not to have retained ESCs and are unable to reproduce asexually. This series provides possible explanation for the exceptional pseudocoelomates and haemocoelomates that reproduce asexually. For posterity, this series intends to bring out six volumes.

August, 2015

T. J. Pandian

Madurai-625 014

Preface

Annelids are known for the unique spectacular epitoky, regeneration and clonal reproduction. These features have attracted attention more from academic interest. An objective of this book is to elevate annelids from academic interest to economic importance. Many books are authored or edited on annelids but are limited to a taxonomic group or a specific theme like phylogeny. This book is a concise, informative elucidation of reproduction and development in annelids covering from Aeolosoma viride to Zeppelina monostyla.

The book is structured in nine chapters. In view of their importance, two chapters are devoted to regeneration and clonal reproduction, a chapter on epitoky and anot...

Table of contents

• Cover
• Halftitle
• Title Page
• Copyright Page
• Table of Contents