Download Sample PDF

For B.Sc. and B.Sc. (Hons.) Classes of all Indian Universities
and also as per UGC Model Curriculum
E.L. Jordan
M.Sc., M.A. (Toronto)
Formerly Head Zoology Department,
Lucknow Christian College, Lucknow
Dr. P.S. Verma
M.Sc., Ph.D., F.E.S.I., F.A.Z.
Formerly Reader Zoology Department
Meerut College, Meerut
S. Chand & Company Ltd.
(An ISO 9001 : 2008 COMPANY)
Ram Nagar, New Delhi - 110055
S. CHAND & COMPANY LTD.
(An ISO 9001 : 2008 Company)
Head Office: 7361, RAM NAGAR, NEW DELHI - 110 055
Phone: 23672080-81-82, 9899107446, 9911310888 Fax: 91-11-23677446
Branches :
Shop at: schandgroup.com; e-mail: [email protected]
Ahmedabad : 1st Floor, Heritage, Near Gujarat Vidhyapeeth, Ashram Road, Ahmedabad - 380 014,
Ph: 27541965, 27542369, [email protected]
Bengaluru : No. 6, Ahuja Chambers, 1st Cross, Kumara Krupa Road, Bengaluru - 560 001,
Ph: 22268048, 22354008, [email protected]
Bhopal : Bajaj Tower, Plot No. 243, Lala Lajpat Rai Colony, Raisen Road, Bhopal - 462 011,
Ph: 4274723. [email protected]
Chandigarh
: S.C.O. 2419-20, First Floor, Sector - 22-C (Near Aroma Hotel), Chandigarh -160 022,
Ph: 2725443, 2725446, [email protected]
Chennai : No.1, Whites Road, Near Clock Tower, Royapettah, Chennai -600014,
[email protected]
Coimbatore : 1790, Trichy Road, LGB Colony, Ramanathapuram, Coimbatore -6410045,
Ph: 0422-2323620, 4217136 [email protected] (Marketing Office)
Cuttack : 1st Floor, Bhartia Tower, Badambadi, Cuttack - 753 009, Ph: 2332580; 2332581,
[email protected]
Dehradun : 1st Floor, 20, New Road, Near Dwarka Store, Dehradun - 248 001,
Ph: 2711101, 2710861, [email protected]
Guwahati : Pan Bazar, Guwahati - 781 001, Ph: 2738811, 2735640 [email protected]
Hyderabad : Padma Plaza, H.No. 3-4-630, Opp. Ratna College, Narayanaguda, Hyderabad - 500 029,
Ph: 24651135, 24744815, [email protected]
Jaipur : 1st Floor, Nand Plaza, Hawa Sadak, Ajmer Road, Jaipur - 302 006,
Ph: 2219175, 2219176, [email protected]
Jalandhar : Mai Hiran Gate, Jalandhar - 144 008, Ph: 2401630, 5000630, [email protected]
Kochi : Kachapilly Square, Mullassery Canal Road, Ernakulam, Kochi - 682 011, Ph: 2378207,
[email protected]
Kolkata : 285/J, Bipin Bihari Ganguli Street, Kolkata - 700 012, Ph: 22367459, 22373914, kolkata@
schandgroup.com
Lucknow : Mahabeer Market, 25 Gwynne Road, Aminabad, Lucknow - 226 018, Ph: 2626801, 2284815,
[email protected]
Mumbai : Blackie House, 103/5, Walchand Hirachand Marg, Opp. G.P.O., Mumbai - 400 001,
Ph: 22690881, 22610885, [email protected]
Nagpur : Karnal Bag, Model Mill Chowk, Umrer Road, Nagpur - 440 032, Ph: 2723901, 2777666 [email protected]
Patna : 104, Citicentre Ashok, Govind Mitra Road, Patna - 800 004, Ph: 2300489, 2302100, patna@
schandgroup.com
Pune : 291/1, Ganesh Gayatri Complex, 1st Floor, Somwarpeth, Near Jain Mandir,
Pune - 411 011, Ph: 64017298, [email protected] (Marketing Office)
Raipur : Kailash Residency, Plot No. 4B, Bottle House Road, Shankar Nagar, Raipur - 492 007,
Ph: 09981200834, [email protected] (Marketing Office)
Ranchi : Flat No. 104, Sri Draupadi Smriti Apartments, East of Jaipal Singh Stadium, Neel Ratan Street,
Upper Bazar, Ranchi - 834 001, Ph: 2208761,
[email protected] (Marketing Office)
siliguri : 122, Raja Ram Mohan Roy Road, East Vivekanandapally, P.O., Siliguri-734001,
Dist., Jalpaiguri, (W.B.) Ph. 0353-2520750 (Marketing Office)
Visakhapatnam: Plot No. 7, 1st Floor, Allipuram Extension, Opp. Radhakrishna Towers, Seethammadhara
North Extn., Visakhapatnam - 530 013, (M) 09347580841, visakhapatnam@schandgroup.
com (Marketing Office)
© 1965, E.L. Jordan & Dr. P.S. Verma
All rights reserved. No part of this publication may be reproduced or copied in any material form (including
photo copying or storing it in any medium in form of graphics, electronic or mechanical means and whether
or not transient or incidental to some other use of this publication) without written permission of the copyright
owner. Any breach of this will entail legal action and prosecution without further notice.
Jurisdiction : All disputes with respect to this publication shall be subject to the jurisdiction of the Courts,
tribunals and forums of New Delhi, India only.
First Edition 1965
Subsequent Editions and Reprints 1968, 70, 73, 74, 76, 77, 78, 80, 81, 83, 86, 87, 88, 89, 90, 91, 93, 95,
96, 97, 98, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009, 2010, 2011, 2012,
14th Revised and Enlarged Edition 2013
ISBN : 81-219-1639-9
Code : 03A 251
printed in india
By Rajendra Ravindra Printers Pvt. Ltd., 7361, Ram Nagar, New Delhi -110 055
and published by S. Chand & Company Ltd., 7361, Ram Nagar, New Delhi -110 055.
DEDICATED
to
My Respected Mother
Late Smt. Gomti Devi
who could not survive
to see the fruits of
this labour
Dr. Prem Singh Verma
Preface To The Fourteenth Edition
The dimensions of biology are fast increasing with more and more emphasis
on cell biology, molecular biology, genetics, biochemistry, physiology, electron
microscopy, biotechnology and development biology (embryology), etc. Many
Indian Universities have already introduced some topics of these disciplines in
their under-graduate syllabi. The importance of basic zoology, however, cannot be
ignored; most teachers and researchers rightly feel the need for a strong base in
general zoology as a prerequisite for all fields of specialisations. Jordan’s “Chordate
Zoology” has served a great deal towards the fulfilment of this aim. It has been a
national best seller for more than four decades. It was, therefore, found necessary
to bring out the same book in more useful and enlarged form. The book has
been thoroughly revised and enlarged in this edition. I have retained all that was
judged good and useful in the previous edition. However, a number of changes
have been made in this edition. Subject matter have been revised and updated
in the light of recent researches and new topics have been added at appropriate
places keeping in view the changes in the syllabi of various Indian Universities.
New chapters and topics which have been added in the present edition
are : (i) Pisces (Fishes) : Labeo rohita (Type study); Comparison of Chondrichthyes
and Osteichthyes; Dipnoi; Fin System; Scales; Air-bladder or Swim-bladder;
Accessary respiratory organs; Parental care; Migration; and Economic importance.
(ii) Amphibia : Parental care; Neoteny and Paedogenesis; Origin and Ancestry.
(iii) Reptilia : Calotes versicolar (Type study); Snakes : General account; Reptilia:
General account. (iv) Aves : Common Flightless birds (Ratitae); Types of beaks and
feet or claws; Types of skull palate; Archaeopteryx and its significance; Birds are
glorified reptiles; Birds as a flying machine; Aerial or flight adaptations; Migration;
and Economic importance. (v) Mammalia : Prototheria (Order Monotremata);
Metatheria; Dentition; Aquatic mammals and adaptations; Flying (Volant) mammals
and adaptations; Adaptive radiations; Adaptive convergence; Origin and Ancestry;
and Economic importance. (vi) Vertebrate Embryology and Comparative Anatomy:
Several new topics have been added. (vii) Wildlife in India. (viii) Glossary.
In addition to this, general topics, which are usually asked in the examinations, have been thoroughly revised and some new topics have also been added
in all the classes of chordates. In the last few years, most of the universities
have introduced long answer type, short answer type, very short answer type
and multiple choice type (objective type) questions in the examination papers. To
cater this requirement, various types of questions have been added at the end
of each chapter.
The examination oriented text is written for all students, even for those
who do not have a good background in the subject. The language is simple,
explanations are clear, and presentation is very systematic. To improve scientific
accuracy, about 706 well-labelled diagrams have been included at appropriate
(v)
places. Important words are given in bold face and definitions in italics. Subject
matter is error free. Notwithstanding several Indian books on Chordate Zoology
or Vertebrate Zoology, I hope the present edition of Chordate Zoology shall serve
the purpose of learned teachers and students.
I am thankful to the Management Team and the Editorial Department of
S. Chand & Company Ltd., for all help and support in the publication of this book.
I like to express my thanks to the esteemed teachers for sending their
valuable suggestions and opinions and shall hope to receive the same in future.
“PREETI”
Dr. P. S. Verma
121, New Mohanpuri Colony,
Meerut- 250 001
Disclaimer : While the authors of this book have made every effort to avoid any mistake or omission and have used
their skill, expertise and knowledge to the best of their capacity to provide accurate and updated information. The
authors and S. Chand do not give any representation or warranty with respect to the accuracy or completeness of the
contents of this publication and are selling this publication on the condition and understanding that they shall not be
made liable in any manner whatsoever. S.Chand and the authors expressly disclaim all and any liability/responsibility
to any person, whether a purchaser or reader of this publication or not, in respect of anything and everything forming
part of the contents of this publication. S. Chand shall not be responsible for any errors, omissions or damages arising
out of the use of the information contained in this publication.
Further, the appearance of the personal name, location, place and incidence, if any; in the illustrations used herein is purely
coincidental and work of imagination. Thus the same should in no manner be termed as defamatory to any individual.
(vi)
Preface To The First Edition
There are some excellent textbooks of comparative anatomy and anatomy
of vertebrates. It would be presumptive to present yet another book on chordate
zoology without any justification. Yet the author feels justified in presenting this
book to the students. Firstly it lays down the basic principles of the B.Sc. Zoology
course of Indian Universities, secondly it is written in a manner which takes into
account the morphology, physiology, histology, embryology, ecology, palaeontology
and evolution of chordates. The book is a comprehensive guide though it does not
burden the student with unnecessary details, yet it is a clear and complete study of
Chordates and it includes not only the study of comparative anatomical structure,
but also the origin of structure in terms of its embryology and evolution. The book
contains numerous clear and well-labelled figures which make an understanding
of the text an easier task.
The first chapter takes into account the geological time chart and the origin
and characters of chordates. Then it deals with Protochordata, but it does not take
into account the Hemichordata. The Hemichordata in modern zoological literature
are now regarded as a separate phylum of invertebrates. Then the Agnatha are
described in outline. The next part is a comprehensive account of the comparative
anatomy of vertebrates dealing with the development, morphology, and evolution
of various systems. This major portion is followed by a classification of vertebrates
along with a description of many representative types from each class. Hardly any
two books have an identical scheme of classification of animals; in this book the
best points of various classifications are taken on the basis of morphology and
evolution, and are coordinated into a wholesome system. The last part of the book
is devoted to general biology dealing with Heredity, Mendelism, and Evolution.
E.L. Jordan
Lucknow,
Ist January, 1965
(vii)
Contents
1. Phylum Chordata : An Introduction
1–13
What is Chordata? 1; Chordate animals 2; Three fundamental
chordate characters 2; Characters common to Chordates and higher
Nonchordates 4; Comparison between Chordates and Nonchordates
5; Origin and ancestry of Chordata 5; Major subdivisions of phylum
Chordata 6; General characters of phylum Chordata 7; Brief
classification of phylum Chordata 7; Brief classification of phylum
Chordata with characters 8; Phylum Chordata 8; Group A. Acrania
(Protochordata) 9; Subphylum I Hemichordata 9; subphylum II
Urochordata or Tunicata 9; Subphylum III Cephalochordata 9; Group
B. Craniata 10; Subphylum IV. Vertebrata 10; Division I. Agnatha 10;
Division II. Gnathostomata 11; Superclass 1. Pisces 11; Superclass
2. Tetrapoda 11; Class 1. Amphibia 11; Class 2. Reptilia 11; Class
3. Aves 12; Class 4. Mammalia 12; Important questions 12.
2.
Type 1. Balanoglossus (A Tongue Worm)
14–34
3.
Subphylum 1. Hemichordata : General Characters;
Classification and Representative Types 35–40
Definition 35; General characters 35; Classification 36; Representative
types 37; Saccoglossus 37; Ptychodera 37; Cephalodiscus 37;
Atubaria 38; Rhabdopleura 39; Important questions 39.
4.
Type 2. Herdmania (A Sea Squirt)
Systematic position 15; Habits and habitat 15; External morphology
16; Body wall 18; Coelom 19; Endoskeleton 20; Digestive system 21;
Respiratory system 24; Blood vascular system 25; Excretory system
26; Nervous system 26; Sense organs 27; Reproductive system 27;
Development 27; Affinities of Balanoglossus 30; Systematic position
and phylogeny 33; Important questions 33.
41–59
Geographical distribution 42; Systematic position 42; Habits and
habitat 42; External morphology 43; General anatomy 47; Digestive
system 48; Respiratory system 51; Circulatory system 52; Nervous
system 54; Receptors 55; Excretory organ 55; Reproductive organs
56; Affinities and Systematic Position of Herdmania (Urochordata) 57;
Important questions 58.
5.
Subphylum 2. Urochordata : General Characters,
Classification and Representative Types
General Characters 60; Classification 61; Representative types
62; Molgula 62; Botryllus 63; Ascidia 63; Ciona 64; Clavelina 64;
Pyrosoma 64; Doliolum 65; Salpa 67; Oikopleura 69; Important
questions 70.
(ix)
60–70
6.
Type 3. Branchiostoma (= Amphioxus) The Lancelet
71–90
Systematic position 72; Geographical distribution 72; Habits and
habitat 72; External features 72; Body wall 74; Skeleton 75; Atrium
75; Coelom 77; Digestive system 78; Respiration 82; Circulatory
system 83; Excretory system 85; Nervous system 86; Sense organs
(Receptors) 87; Reproductive system 88; Important questions 89.
7.
Subphylum 3. Cephalochordata : General Characters,
Primitive, Degenerate and Specialised Characters and
Affinities
91–95
General characters 91; Primitive, Degenerate and Specialised
characters of Branchiostoma (Cephalochordata) 92; Affinities of
Cephalochordata 93; Important questions 94.
8.
Protochordata : General and Comparative
What are protochordates? 96; Significance of protochordates 97;
Comparison of three protochordate subphyla 97; General comparison
of three protochordate subphyla at a glance 97; Comparison : Habits
and habitat of three protochordate types 98; Comparison : External
features of three protochordate types 99; Comparison : Digestive
system (Alimentary canal and associated glands) of three protochordate types 99; Comparison : Pharynx of three protochordate
types 101; Comparison : Food and feeding mechanism of three
protochordate types 102; Comparison : Excretory system of three
protochordate types 103; Comparison : Nervous system of three
protochordate types 104; Comparison : Circulatory system of
three protochordate types 105; Comparison : Reproduction of three
protochordate types 106; Important questions 106.
96–107
9. Subphylum 4. Vertebrata : General Characters, Origin and
Ancestry of Vertebrates
108–119
What are vertebrates? 108; Chordate versus vertebrates 109; General
Characters of subphylum Vertebrata 109; Diversity of vertebrates 110;
Selected characters of classes 111; Phylogeny or Evolutionary history
of vertebrates 111; Origin and ancestry of vertebrates (chordates)
113; Important questions 119.
10.
Class 1. Ostracodermi (Extinct) : General Characters,
Classification and Representative Types 120–124
Occurrence 120; Important features 121; Classification 121; Biological
significance of ostracoderms 123; Inter-relationship and affinities 123;
Important questions 123.
11. Type 4. Petromyzon (The Lamprey)
Systematic
position 126; Distribution 126; Habits and habitat 126;
External features 127; Anatomy and physiology 128; Body wall
128; Muscular system 129; Skeleton 129; Digestive System 130;
(x)
125–139
Respiratory system 130; Circulatory System 131; Nervous system
131; Sense organs 132; Excretory system 132; Reproductive system
133; Life history 133; Ammocoete larva 134; Metamorphosis 134;
Comparison between lamprey and hagfishes 134; Summary of
characters of cyclostomes: Affinities of cyclostomes 136; Important
questions 137.
12. Class 2. Cyclostomata : General Characters,
Classification and Representative Types 140–143
General characters 140; Classification 141; Representative types 141;
Important questions 143.
13.
Class 3. Placodermi (Extinct) : General
Characters and Classification
Earliest jawed vertebrates 144; Occurrence 145; Important features
145; Classification 145; Biological significance 146; Important
questions 146.
14.
Type 5. Scoliodon : A Cartilaginous Fish (The Dogfish)
144–146
147–194
Systematic position 148; Distribution 148; Habits and habitat 148;
External features 148; Skin 151; Exoskeleton 151; Endoskeleton
153; Musculature 159; Locomotion 160; Coelom and viscera 161;
Digestive system 163; Respiratory system 166; Blood vascular system
168; Nervous system 176; Receptor organs (Sense organs) 180;
Urinogenital organs 186; Reproduction 189; Economic importance
191; Important questions 191.
15.
Type 6. Labeo rohita : Rohu (A Bony Fish)
195–212
Systematic position 196; Distribution 196; Habits and habitat 196;
External Features 196; Body wall or Integument 197; Exoskeleton
197; Endoskeleton 197; Digestive system 203; Air-bladder (Swimbladder) 205; Respiratory system 205; Blood vascular system 207;
Nervous system 208; Urinogenital system 210; Economic importance
211; Important questions 212.
16.
Superclass Pisces : General Characters, Classification and
Representative Types
213–236
General characters 213; Classification 214; Class 4. Chondrichthyes
215; Classification of Chondrichthyes 215; Some representative types
of Chondrichthyes 216; Class 5. Osteichthyes 219; Classification of
Osteichthyes 219; Some representative types of Osteichthyes 223;
Lobe-finned fish 223; Lung fish 224; Ganoid fish 226; Advanced rayfinned bony fishes 228; Important questions 235.
(xi)
17.
Superclass Pisces and Fish : General Account
Comparison of Chondrichthyes and Osteichthyes 237; Dipnoi 239;
Fin system 245; Scales of fishes 249; Air-bladder or Swim-bladder
251; Accessory respiratory organs 255; Parental care in fishes 259;
Migration in fishes 261; Economic importance of fishes 263; Important
questions 266.
18.
Type 7. Rana tigrina (Common Indian Bull Frog)
237–267
268–330
Systematic position 269; Habit and habitat 269; External features
271; Skin 274; Endoskeleton 276; Digestive system 284; Respiratory
system 296; Blood vascular system 300; Arterial system 304; Venous
system 306; Lymphatic system 307; Blood 308; Nervous system 311;
Receptors 318; Urinogenital system 324; Important questions 329.
19.
Class 6. Amphibia : General Characters, Classification and
Representative Types
331–341
General characters 331; Classification 332; Representative types 334;
Important questions 341.
20.Amphibia : General Account
Parental care in Amphibia 342; Neoteny and Paedogenesis 345; Origin
and Ancestry of Amphibia (Tetrapoda) 346; Important questions 349.
21.
Type 8. Uromastix hardwickii (The Spiny-Tailed Lizard)
342–349
350–390
Systematic position 351; Habit and habitat 352; External features
353; Skin or Integument 355; Exoskeleton 355; Endoskeleton 356;
Skeleton of Varanus 356; Digestive system 369; Respiratory system
372; Blood vascular system 374; Arterial system 377; Venous system
379; Nervous system 381; Sense organs 384; Urinogenital system
387; Excretory system 387; Male genital organs 388; Female genital
organs 389; Copulation and fertilisation 389; Important questions 390.
22.
Type 9. Calotes versicolor (The Garden Lizard) 391–404
Systematic Position 391; Natural history 391; External features 392;
Digestive system 393; Respiratory system 394; Blood vascular system
395; Arterial system 396; Venous system 398; Nervous system 399;
Excretory system 402; Reproductive system 402; Important questions
404.
23.
405–414
Snakes : General Account External features 406; Hearing 406; Feeding mechanism 406; Poison
apparatus 407; Biting mechanism 409; Swallowing mechanism 410;
Snake venom 410; Types of venom 410; Treatment 411; Distinction
between poisonous and non-poisonous snakes of India 411; Key for
identification of poisonous and non-poisonous snakes of India 413;
Important questions 414.
(xii)
24. Class 7. Reptilia : General Characters, Classification and
Representative Types
415–437
General Characters 415; Classification 417; Representative types 419;
Turtles and tortoises 419; Sphenodon 422; Lizards 424; Snakes 427;
Non-poisonous snakes 427; Poisonous snakes 429; Crocodilia 432;
Important questions 436.
438–443
25.
Reptilia : General Account Origin of reptiles 438; Adaptive radiation in reptiles 440; Dinosaurs
440; Important questions 443.
26.
Type 10. Columba livia (The Common Rock Pigeon)
Early history (Origin) 444; Characteristics of Aves 445; Systematic
position 446; Habit and habitat 447; Distribution 447; External features
448; Skin 450; Exoskeleton 450; Muscular system 459; Endoskeleton
of Fowl (Gallus) 462; Coelom and viscera 475; Digestive system,
476; Respiratory system 479; Circulatory system 483; Arterial system
486; Venous system 487; Nervous system 490; Sense organs 493;
Endocrine glands 498; Urinogenital system 498; Urinary or Excretory
organs 498; Male reproductive organs 499; Female reproductive
organs 499; Copulation 501; Important questions 501.
27.
Class 8. Aves (The Birds) : General Characters,
Classification, and Representative Types General Characters 505; Classification 506; Representative Types
511; Archaeopteryx 511; Common Birds of India 513; Important
questions 520.
28.Aves (Birds) : General Account Flightless birds (Ratitae) 521; Origin of birds 526; Origin of flight in
birds 528; Birds are glorified reptiles 529; Birds as a flying machine
530; Modes of flight 532; Flight or aerial adaptations of birds 534;
Beaks of birds 537; Types of feet or claws in birds 539; Palate in
birds 541; Migration of birds 543; Economic importance of birds 549;
Important questions 552.
29.
Type 11. Oryctolagus (The Rabbit)
Distinguishing characters 554; Systematic position 554; Habit and
habitat 555; Distribution 555; Enemies 555; Economic importance
555; Important adaptations 556; Rabbit and hare 556; External
features 557; Locomotion 559; Integument 559; Endoskeleton 564;
Axial skeleton 564; Appendicular skeleton 574; Coelom and viscera
577; Digestive system 579; Respiratory system 594; Blood vascular
system 599; Heart 599; Blood vessels 603; Arterial system 603;
Venous system 605; Hepatic portal system 607; Blood 607; Lymphatic
system 608; Nervous system 609; Central nervous system 609;
(xiii)
444–503
504–520
521–552
553–641
Peripheral nervous system 613; Autonomic nervous system 616;
Sense organs 617; Urinogenital system 626; Excretory system, 626;
Reproductive system 629; Endocrine system 633; Important questions
639.
30. Class 9. Mammalia : General Characters, Classification and
Representative Types
642–673
General characters 642; Classification 643; Representative types 651;
Important questions 672.
31.
Subclass Prototheria (Order Monotremata)
Distinctive characters 674; Habit and habitat 674; External features
675; Exoskeleton 675; Body cavity 675; Endoskeleton 675;
Digestive system 677; Respiratory system 677; Circulatory system
677; Excretory system 677; Nervous system 678; Receptors 678;
Reproductive system 678; Development 678; Classification of
Prototheria 679; Affinities of Prototheria 679; Important questions 681.
32.
Infraclass Metatheria (Order Marsupialia)
674–681
682–688
Distinctive characters 683; Distribution 683; Habits and habitat
683; External features 683; Exoskeleton 683; Body cavity 683;
Endoskeleton 683; Digestive system 684; Respiratory, circulatory and
excretory system 684; Nervous system 684; Reproductive system 684;
Development 684; Classification of Marsupialia 685; Distribution of
Metatheria 686; Affinities of marsupials 687; Systematic position 688;
Phylogenetic consideration of Metatheria (Marsupialia) 688; Important
questions 688.
33.
Mammalia : General Account
Dentition in mammals 689; Aquatic mammals and adaptations 697;
Flying (Volant) mammals and adaptations 700; Adaptive radiation in
mammals 702; Adaptive convergence in mammals 704; Origin and
ancestry of mammals 706; Economic importance of mammals 708;
Important questions 712.
34.
Introduction to Vertebrate Embryology
689–712
713–726
Historical review 714; Modern embryology 715; Scope of embryology
716; Gametogenesis 716; Embryonic development 716; Types of
eggs 717; Classification of eggs on the basis of amount of yolk 717;
Fertilisation 719; Cleavage 720; Stages of embryogeny 722; Morula
722; Blastula 722; Gastrula 722; Organogeny 723; Derivatives of
germ layers 723; Important questions 725.
35.
727–733
Development of Herdmania Gametes 727; Fertilisation 728; Presumptive areas 728; Embryonic
or prelarval development 728; Larval development 729; Tadpole larva
729; Retrogressive metamorphosis 730; Embryological significance
of Ascidian tadpole 732; Important questions 733.
(xiv)
36.
Development of Branchiostoma (Amphioxus)
734–747
Gametes 734; Fertilisation 735; Presumptive areas 736; Early
embryonic development 736; Cleavage and blastulation 736;
Gastrulation 737; Fate of germ cells 738; Formation of notochord 738;
Formation of neural tube 738; Development of mesoderm and coelom
740; Further development of coelom 740; Differentiation of myotome
740; Development of head 742; Development of gut 742; Hatching
of larva 742; Post-hatching development 742; Metamorphosis 746;
Important questions 746.
37.
748–761
Development of Frog Spawning 748; Fertilisation 749; Cleavage and blastulation 749;
Presumptive areas 750; Gastrulation 750; Neurulation 753;
Notogenesis 754; Post-neural or pre-hatching development 756; Posthatching development of tadpole 756; Metamorphosis 758; Important
questions 760.
38.
Development of Chick (Fowl)
Fertilisation
762–777
763; Structure of egg of hen 763; Cleavage and
blastulation 764; Presumptive fate maps of blastula 766; Gastrulation
766; Formation of primitive streak 767; Formation of neural tube
(Neurogenesis) 769; Formation of notochord and mesoderm 769;
Formation of somites 769; Formation of coelom 770; Folding of embryo
771; Flexure and torsion 772; Extra-embryonic (Foetal) membranes of
chick 772; Development of extra-embryonic membranes 772; Hatching
775; Important questions 775.
39.
778–785
Development of Rabbit
Egg 778; Fertilisation 779; Early embryonic development 779;
Cleavage 779; Blastocyst 779; Implantation 780; Gastrulation 781;
Neurulation 782; Development of extra-embryonic membranes of
rabbit 782; Development of amnion and chorion 782; Development
of allantois 783; Development of yolk-sac 784; Important questions
784.
40.
Placenta and Placentation in Mammals Mode of origin and types of mammalian placentae 787; Choriovitelline placenta or chorionic placenta or yolk-sac placenta 787;
Chorio-allantoic placenta or Allantoic placenta 787; Classification of
chorio-allantoic placenta 788; Morphological classification of placenta
788; Classification of placentae according to the distribution of villi
on chorion 789; Classification of placenta according to histology 790;
Classification of placentae according to the mode of implantation 791;
Physiology of placenta 792; Important questions 793.
41.
Integument and its Derivatives in Vertebrates
Structure of skin 795; Functions of integument 796; Derivatives of
(xv)
786–794
795–814
the integument 797; Epidermal derivatives 798; Epidermal glands
798; Epidermal scales and scutes 800; Horns 802; Digital structures
803; Feathers 804; Hair 805; Dermal derivatives 806; Integument in
different classes of chordates 809; Protochordata 811; Cyclostomata
809; Pisces 809; Amphibia 810; Reptilia 811; Aves 812; Mammalia
812; Important questions 813.
42.
Endoskeleton in Vertebrates
Dermal bony skeleton 815; Endoskeleton 815; Functions of
endoskeleton 816; Bone 816; Axial skeleton 818; Skull 818; Skull in
various classes of vertebrates 824; Cyclostomata 824; Chondrichthyes
824; Osteichthyes 824; Amphibia 824; Reptilia 825; Aves 825;
Mammalia 826; Vertebral column 826; Vertebral column in fishes
831; Vertebral column in tetrapoda 832; Amphibia 833; Reptilia 833;
Aves 833; Mammalia 834; Sternum 834; Pisces 835; Amphibia 835;
Reptilia 835; Aves 835; Mammalia 835; Appendicular skeleton 835;
Origin of appendages 835; Origin of girdles 837; Girdles and limbs in
tetrapoda 837; Limbs 837; Origin of pentadactyle limbs 838; Girdles
and limbs in Tetrapoda 838; Muscles 842; Swimming in bony fishes
843; Swimming in snakes 844; Important questions 845.
43.
Coelom and Digestive System in Vertebrates
Coelom 846; Digestive system 849; Buccal cavity 850; Pharynx 853;
Oesophagus 853; Stomach 853; Small intestine 855; Large intestine
856; Digestive glands 857; Important question 858.
44.
Respiratory System in Vertebrates 815–845
846–858
859–866
Respiratory organs 860; Gills 860; Lungs 862; Mechanism of
respiration 864; Accesory respiratory organs 864; Important questions
866.
45.
Circulatory System in Vertebrates
867–880
Parts
of circulatory system 868; Evolution of heart in vertebrates
869; Single-chambered heart 869; Two-chambered heart 870; Threechambered heart 870; Four-chambered heart 872; Modification of
aortic arches in vertebrates 872; Aortic arches in vertebrates 873;
Cyclostomata 873; Pisces 873; Amphibia 873; Reptilia 873; Aves
874; Mammalia 874; Venous system 875; Modifications of veins 876;
Lymphatic system 877; Spleen 879; Important questions 880.
46.
Nervous System in Vertebrates Nervous system and its functions 881; Anatomy of nervous system:
The neuron 882; Divisions of nervous system 883; Functional divisions
of nervous system 884; Kinds of neurons 884; Development of central
nervous system 885; Comparative account of brain in vertebrates
888; Cyclostomata 888; Elasmobranchi 889; Osteichthyes (Bony
(xvi)
881–896
fish) 891; Amphibia 891; Reptilia 891; Aves 891; Mammalia 892;
Peripheral nervous system 893; Cranial nerves 894; Spinal nerves
894; Autonomic nervous system 895; Important questions 896.
47.
Receptor Organs in Vertebrates Cutaneous (General) receptors 898; Chemoreceptors 899; Olfactory
organs in vertebrates 899; Gustatory or organs of taste in vertebrates
900; Eyes or Photoreceptors 900; Lateral line system 902; Ears or
Statoacoustic organs 903; Internal receptors or Interoceptors 904;
Important questions 905.
48.
Urinogenital Organs in Vertebrates
Vertebrate kidneys and ducts 907; Archinephros 907; Pronephros 908;
Mesonephros 909; Metanephros 911; Urinary bladder 912; Gonads
and their ducts 912; Testes and male genital ducts 913; Ovaries and
female genital ducts 914; Types of uterus 917; Important questions
917.
897–905
906–917
Endocrine System in Vertebrates 918–936
50.
Some Comparative Charts of Vertebrate Animal Types
937–999
Table 50.1. Comparison, Distribution, Habits and Habitat of Vertebrate
Types 938; Table 50.2. Comparison : External Features of Vertebrate
Types 940; Table 50.3. Comparison : Integument of Vertebrate Types
945; Table 50.4. Comparison : Exoskeletal Structures of Vertebrate
Types 947; Table 50.5. Comparison : Skulls of Vertebrate Types
949; Table 50.6. Comparison : Pectoral Girdles (Shoulder Girdles) of
Vertebrate Types 952; Table 50.7. Comparison : Pelvic Girdles (Hip
Girdles) of Vertebrate Types 956; Limbs of Vertebrate Types 959;
Table 50.8. Comparison : Bones of Forelimbs of Vertebrate Types
960; Table 50.9. Comparison : Bones of Hindlimbs of Vertebrate Types
962; Table 50.10. Comparison : Vertebral Column of Vertebrate Types
964; Table 50.11. Comparison : Digestive System of Vertebrate Types
969; Table 50.12. Comparison : Respiratory System of Vertebrate
Types 977; Table 50.13. Comparison : Hearts of Vertebrate Types
980; Table 50.14. Comparison : Brains of Vertebrate Types 985;
Table 50.15. Comparison : Excretory Systems of Vertebrate Types
991; Table 50.16 Comparison : Reproductive Systems of Vertebrate
Types 994.
49.
Endocrine and exocrine glands 918; Endocrine glands 919; Thyroid
gland 920; Parathyroid glands 921; Adrenal glands 922; Pituitary gland
923; Thymus gland 925; Pineal gland 926; Pancreas 926; Mucous
membrane 927; Gonads 927; Endocrine glands in vertebrates 928;
Elasmobranchii 928; Amphibia 928; Reptilia 929; Aves 929; Molecular
mechanisms of hormone action 929; Pheromones 934; Important
questions 935.
(xvii)
1000–1045
51.
Wildlife in India Importance of wildlife 1001; Biodiversity 1003; Magnitude of
biodiversity 1004; Status of biodiversity 1004; Uses of biodiversity
1004; Threats to biodiversity 1004; Vanishing wildlife 1004; Causes
of destruction 1005; Conservation, Preservation, Protection and
Categories of Wild Animals 1007; Extinction of species 1007;
Extinct species 1007; Endemic species 1008; The IUCN Red List of
Categories 1008; Protected Indian wildlife 1009; Table 51.1. IUCN Red
List of Some Indian Threatened Mammals 1009; Table 51.2. IUCN
Red List of Some Indian Threatened Reptiles 1011; Table 51.3. IUCN
Red List of Some Threatened Indian Birds 1011; Protected areas
in India 1013; National Parks 1014; Sanctuaries 1014; Biosphere
Reserves 1014; Safari Park 1014; Zoo 1014; Zoological Garden
1014; Zoological Park 1014; Sanctum sanctorum 1014; Conservation
of wildlife 1014; Conservation strategies 1015; Important Indian
wildlife 1016; Table 51.4. Endangered Species of Indian Hornbills
1021; Project Tiger 1021; Table 51.5. Details of Tiger Reserves in
India 1022. Project Lion (Gir Lion Project) 1023; Project Elephant
1024; Crocodile Breeding Project 1024;Table 51.6. Schemes of the
Government of India Project, Crocodile Breeding and Management
operating with FAO/UNDP Technical Assistance 1026; Sanctuary and
National Park 1027; Table 51.7. Differences between Sanctuary and
National Park 1028; Indian Sanctuaries 1028; Table 51.8. Statewise
Break-up of Wildlife Sanctuaries 1029; National Parks 1030; Table
51.9. Statewise Break-up of National Parks of India 1031; Some
National Parks of India 1032; Table 51.10. Famous National Parks
of World created for Specific Endangered Species 1035; Table
51.11. Some Wildlife Sanctuaries and National Parks of India 1035;
Biosphere Reserves 1037; Table 51.12. Biosphere Reserves of India
1038; Zoological Gardens and Museums 1039; Table 51.13. Some
Indian Zoological Gardens and Museums 1039; Wildlife Organisations
1040; Wildlife Institute of India (WII) 1042; Wildlife Act 1042; Need
of Wildlife Management / Conservation 1043; Problems of Wildlife
Management in India 1044; Methods of Wildlife Conservation 1044;
Important questions 1045.
Glossary
1046–1065
Selected References
1066–1069
Index1070–1076
(xviii)
1
Phylum Chordata :
An Introduction
C h a p t e r
Contents of this Chapter
What is ChordatA ?
The name of phylum Chordata is derived from two Greek
words, the chorde ( = a string or cord) and ata (= bearing).
The common characteristic feature of phylum Chordata is
the presence of a stiff, supporting rod-like structure along
the back, the notochord (Gr., noton = back; L. chorda
= cord) which is found in all the members of the phylum at
some stage of their lives. Thus, chordates are those animals
which have a cord, i.e., notochord. The animals belonging to
all other phyla of the Animal Kingdom are often called “the
nonchordates” or “the invertebrates” since they do not have
notochord or backbone in their body structure. The phylum
Chordata was created by Balfour in 1880. The phylum
Chordata includes primarily the Protochordata (Acraniata)
and Vertebrata (Craniata).
Ü What is Chordata?
Ü Chordate Animals
Ü Three Fundamental Chordate
Characters
Ü Characters Common to
Chordates and Higher
Nonchordates
Ü Comparison between Chordates
and Nonchordates
Ü Origin and Ancestry of Chordata
Ü Major Subdivisions of Phylum
Chordata
Ü General Characters of Phylum
Chordata
Ü Brief Classification of Phylum
Chordata with Characters
Ü Phylum Chordata
2
Chordate Zoology
Chordate Animals
Phylum Chordata is the largest of the deuterostome phyla. It is the highest and most important
phylum comprising a vast variety of living and extinct animals. Most of the living chordate animals are
well-known familiar vertebrate animals such as the fishes, amphibians, reptiles, birds and mammals.
The less well-known animals include a number of marine forms such as the tunicates and
lencelets.
Diversity of Chordates
The chordates exhibit great diversity of form (anatomy), physiology and habit. The phylum
Chordata includes a vast group of diverse animals ranging from Ascidian to Man.
Number (Numerical strength). The number of chordate species is not large. About 49,000
species are on record which are only half of the living species of molluscs, and less than onetenth those of arthropods. The two subphyla Urochordata and Cephalochordata include nearly
2,500 species. The subphylum Vertebrata includes 46,500 species. Among the vertebrates, fishes
are the most numerous with approximately 25,000 species. The approximate number of species
of amphibians is about 2,500, reptiles 6,000, birds 9,000 and mammals 4,500.
Size. The urochordates and cephalochordates are mostly of small size. The vertebrates
include animals of medium to large size, notably some huge sharks and whales. The gigantic blue
whale (Balaenoptera musculus), which is about 35 metres in length and 120 tons in weight, is
the biggest known animal. The whale shark (Rhineodon typus) attains a length of 15 metres and
is the second biggest vertebrate after whales. The smallest fish is a Philippine goby (Pandaka)
measuring only 10 mm long.
Ecology. The chordates are not only the largest animals existing today, but ecologically they
are among the most successful in the Animal Kingdom. They occupy various kinds of habitats
and have adapted themselves to various modes of living than any other group, including the
arthropods. Chordates are found in the sea, in freshwater, in the air and all parts of land from
the equator to the poles. Birds and mammals are found in cold climates because they have a
constant body temperature, which other animals do not have.
All lower chordates (protochordates) are marine, fishes are aquatic (freshwater and marine
both) and higher chordates are predominantly terrestrial. Amphibians are not found in salt
water. Birds do not live permanently in water, while some amphibians, reptiles and mammals
permanently occupy the water. Most tunicates are sessile, all chordates are free-living and none
is strictly parasitic.
Three Fundamental Chordate Characters
All the chordates possess three common fundamental characteristics at some stage in their
life history. These three common fundamental morphological features are as follows :
1.Notochord (a longitudinal supporting rod-like structure);
2.Dorsal tubular (hollow) nerve cord; and
3.Pharyngeal gill-slits.
These three distinctive characteristics are unique for the phylum Chordata (Fig. 1.1). The
existence of such common characteristics is considered as a result of inheritance from a common
ancestry. Besides these three common characteristics, there are few other characteristics which
have less diagnostic value.
1. Notochord or chorda dorsalis. The notochord (Gr., noton = back; chorda = cord) is
a rod-like, elongated, elastic structure situated just above the alimentary canal and immediately
beneath the dorsal tubular nerve cord. It is composed of large vacuolated notochordal cells
enclosed in an outer fibrous and an inner elastic sheath of connective tissue (Fig. 1.2). It serves
as a primitive internal skeleton and acts as a rigid axis, but permits movements of the body.
It may persist throughout life, as in lancelet, lamprey and some fishes, or it may be replaced
3
Phylum Chordata : An Introduction
partially or completely by a backbone or vertebral column. The notochord originates from the
endodermal roof of the embryonic archenteron.
pharyngeal gills-slits
fibrous neural
sheath
dorsal hollow nerve cord
cartilage
notochord
fibrous
notochordal
sheath
anus
mouth
pharynx
trunk
hepatic caecum
nerve cord
tail
digestive tube
Fig. 1.1.Diagrammatic side view of a chordate showing
three fundamental chordate characters.
notochordal
cells
elastica
interna
cartilage
dorsal aorta
Fig. 1.2.Notochord of young dogfish.
2. Dorsal tubular nerve cord. In chordates, there is a dorsal, hollow or tubular, fluid-filled
nerve cord lying just above the antero-posterior axis of the body (Fig. 1.2). The nerve cord is
formed by an infolding of mid-dorsal strip of neural ectoderm and encloses a cavity or canal,
the neurocoel. The nerve cord lies above the notochord and outside the coelom, extending lengthwise in the body. This tubular nerve cord persists throughout the life in chordates.
In vertebrates, the anterior region of nerve cord becomes specialised to form a cerebral vesicle
or brain which is enclosed in a protective cartilaginous or bony cranium. The posterior part of nerve
cord transforms into spinal cord which is protected within the neural canal of the vertebral column.
3. Pharyngeal gill-slits. The gill-slits have many alternative names, such as gill-clefts,
pharyngeal or branchial-clefts, visceral-clefts, visceral or branchial-pouches. In all the chordates, at
some stage of their life history, a series of paired internal gill-slits or gill-clefts perforate through
the pharyngeal wall of the gut behind the mouth. Gill-slits are paired openings leading from the
pharynx to the exterior. Lateral outpushing of the endodermal lining of pharynx meet and fuse
with ectodermal inpushings from the exterior, the intervening walls being broken down, thus,
gill-clefts are formed. Such gill-clefts appear during the development of every chordate, but in
many aquatic forms they are lined with vascular lamellae which form gills for respiration. In
terrestrial chordates which never breathe by gills, traces of gill-clefts are present during early
development but disappear later in adults. Within these clefts are the gills in many aquatic animals.
In many animals equipped with lungs, branchial-clefts, or branchial-grooves are always found in
the embryo. In lower chordates, the visceral-clefts are used as a feeding mechanism throughout
life, but in higher chordates, the gill-clefts often form some endocrine glands.
The gill-slits serve primarily for the passage of the water from the pharynx to outside,
thus, bathing the gills for respiration. The water current secondarily helps in filter feeding by
retaining food particles in the pharynx.
The above three common characters appear during early embryonic life of all the chordates.
But all the above three characters rarely persist in the adult (e.g., Branchiostoma). Only one of
these three primary characters of chordates is found in the adults of most of them, this is the dorsal
tubular nerve cord, even this has its hollow lumen greatly reduced in some, and in Urochordata the
central nervous system degenerates in the adult. The other two characters completely disappear in
the adults of most chordates. However, the three primary characters are possessed only by chordates.
The three common chordate characters were probably characteristics of the ancestral chordates.
These characters distinguish chordates from all other animals and appear to reveal their common
ancestry.
Chordate Zoology
30%
OFF
Publisher : SChand Publishing
ISBN : 9788121916394
Author : E L Jordan & Dr.
P.S. Verma
Type the URL : http://www.kopykitab.com/product/5954
Get this eBook