1st Edition

Reproduction and Development in Echinodermata and Prochordata

ISBN 9780815364726
Published April 5, 2018 by CRC Press
270 Pages 59 B/W Illustrations

USD $190.00

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Book 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




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


Capture Fisheries


Sexual Reproduction






Reproductive Cycle

Asexual Reproduction


Types and Characteristics

Fission and Reproduction

Clonal and Sexual Reproduction

Induced Fission

The Trigger

Clonal Autotomy

Larval Cloning

Eggs and Embryos

Searching Stem Cells



Incidence and Prevalence

Induction of Autotomy

Causes and Consequences

Growth and Differentiation

Growth Factors and Genes

Sex Determination


Species and Fidelity

Karyotypes and Heteromorphism

Ploidy Induction

Genome and Sequencing

Sex Differentiation


Asteroid Model

Echinoid Model

Induction of Spawning

Endocrine Disruption

Parasitic Disruption


Reproductive Biology


Life Cycles

Gonads and Consequences

Regeneration in Enteropneusts




Reproductive Biology



Pelagic Tunicates

Benthic Tunicates

Germline Lineage

New Findings and Highlights


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


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