Reproduction and Development in Echinodermata and Prochordata

Nonfiction, Science & Nature, Science, Biological Sciences, Marine Biology, Nature, Animals
Cover of the book Reproduction and Development in Echinodermata and Prochordata by T. J. Pandian, CRC Press
View on Amazon View on AbeBooks View on Kobo View on B.Depository View on eBay View on Walmart
Author: T. J. Pandian ISBN: 9781351106917
Publisher: CRC Press Publication: April 17, 2018
Imprint: CRC Press Language: English
Author: T. J. Pandian
ISBN: 9781351106917
Publisher: CRC Press
Publication: April 17, 2018
Imprint: CRC Press
Language: English

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.

View on Amazon View on AbeBooks View on Kobo View on B.Depository View on eBay View on Walmart

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.

More books from CRC Press

Cover of the book Modern Digital Design and Switching Theory by T. J. Pandian
Cover of the book Models for Design by T. J. Pandian
Cover of the book How to Cheat in 3ds Max 2010 by T. J. Pandian
Cover of the book Exploring Natural Hazards by T. J. Pandian
Cover of the book How to Cheat in Maya by T. J. Pandian
Cover of the book Laser Precision Microprocessing of Materials by T. J. Pandian
Cover of the book Integrated Molecular Evolution by T. J. Pandian
Cover of the book BTEC National for IT Practitioners: Business units by T. J. Pandian
Cover of the book Building Energy Simulation by T. J. Pandian
Cover of the book Cells in Evolutionary Biology by T. J. Pandian
Cover of the book Advanced Nanoelectronics by T. J. Pandian
Cover of the book Essentials of Probability Theory for Statisticians by T. J. Pandian
Cover of the book Power Electronic Converters by T. J. Pandian
Cover of the book Chemistry of Plant Hormones by T. J. Pandian
Cover of the book McMinn's Concise Human Anatomy by T. J. Pandian
We use our own "cookies" and third party cookies to improve services and to see statistical information. By using this website, you agree to our Privacy Policy