Reproduction and Development in Echinodermata and Prochordata: 1st Edition (Hardback) book cover

Reproduction and Development in Echinodermata and Prochordata

1st Edition

By T. J. Pandian

CRC Press

270 pages | 59 B/W Illus.

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Description

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.

Table of Contents

NON-CHORDATE-DEUTEROSOMIA

ECHINODERMATA

Introduction

Taxonomy and Structural Diversity

Distribution, Locomotion and Dispersal

Population Density and Microhabitats

Energy Budget and Reproduction

Gonad Index and Fecundity

Egg Size and its Implications

Larval Development and Thyroid Hormones

Brooding and Viviparity

Size and Life Span

Fisheries and Aquaculture

Introduction

Capture Fisheries

Aquaculture

Sexual Reproduction

Introduction

Sexuality

Gonochorism

Parthenogenesis

Hermaphroditism

Reproductive Cycle

Asexual Reproduction

Introduction

Types and Characteristics

Fission and Reproduction

Clonal and Sexual Reproduction

Induced Fission

The Trigger

Clonal Autotomy

Larval Cloning

Eggs and Embryos

Searching Stem Cells

Regeneration

Introduction

Incidence and Prevalence

Induction of Autotomy

Causes and Consequences

Growth and Differentiation

Growth Factors and Genes

Sex Determination

Introduction

Species and Fidelity

Karyotypes and Heteromorphism

Ploidy Induction

Genome and Sequencing

Sex Differentiation

Introduction

Asteroid Model

Echinoid Model

Induction of Spawning

Endocrine Disruption

Parasitic Disruption

HEMICHORDATA

Reproductive Biology

Introduction

Life Cycles

Gonads and Consequences

Regeneration in Enteropneusts

CHORDATE DEUTEROSTOMIA

Cephalochordata

Introduction

Reproductive Biology

Urochordata

Introduction

Pelagic Tunicates

Benthic Tunicates

Germline Lineage

New Findings and Highlights

Introduction

Structure and Distribution

Fecundity, Size and Depth

Aquaculture: Sea Urchins and Cucumbers

Intromittent Organ

Gonad and Hormonal Economy

Regenerative Potential

Gonads of Cloners

Clonal Reproduction

Autoregulation and Stem Cells

Cloning and Coloniality

References

About the Series

Reproduction and Development in Aquatic Invertebrates

Learn more…

Subject Categories

BISAC Subject Codes/Headings:
NAT001000
NATURE / Animals / General
SCI039000
SCIENCE / Life Sciences / Biology / Marine Biology
SCI072000
SCIENCE / Life Sciences / Biology / Developmental Biology
SCI086000
SCIENCE / Life Sciences / General