Phylum chordates pptx free to use for students
- 1. Classification of Phylum-Chordates Presented By-: Ms. Amita Saxena Assistant Professor Department of Zoology St. Aloysius’ College (Autonomous), Jabalpur
- 3. General Characters of Phylum Chordata (L. chordatus, having a cord, i.e., the notochord). (1) Aquatic, aerial or terrestrial. All free-living with no fully parasitic forms. (2) Body small to large, bilaterally symmetrical and metamerically segmented. (3) A postanal tail usually projects beyond the anus at some stage and may or may not persist in the adult. (4) Exoskeleton often present; well developed in most vertebrates. (5) Bodywall triploblastic with 3 germinal layers : ectoderm, mesoderm and endoderm. (6) Coelomate animals having a true coelom, enterocoelic or schizocoelic in origin. (7) A skeletal rod, the notochord, present at some stage in life cycle.
- 4. 8. A cartilaginous or bony, living and jointed endoskeleton present in the majority of members (vertebrates). 9. Pharyngeal gill slits present at some stage, may or may not be functional. 10. Digestive system complete with digestive glands. 11. Blood vascular system closed. Heart ventral with dorsal and ventral blood vessels. Hepatic portal system well developed. 12.Excretory system comprising proto-or meso-or meta- nephric kidneys. 13. Nerve cord dorsal and tubular. Anterior end usually enlarged to form brain. 14.Sexes separate with rare exceptions.
- 7. Subphylum 1. Hemichordata (Gr. hemi, half; chorde, cord). Body divided into 3 regions : proboscis, collar and trunk. Notochord doubtful, short, confined to proboscis arid non- homologous with that of chordates. But recent workers consider the so-called notochord of the hemichordates not a true notochord but a ' stomochord‘ (a flexible, hollow tube) Hence the hemichordates are removed from the chordates and treated as an independent invertebrate phylum.
- 8. Class 1. Enteropneusta. (Gr. enteron, gut; pneustos, breathed). Body large and worm-like. Gill-slits numerous. Intestine straight. Acorn or tongue worms. 3 families, 15 genera and 70 species. Balanoglossus, Saccoglossus, Class 2. Pterobranchia. (Gr. pteron, feather; branchion, gill). Body small and compact. Gill-slits one pair or none. Intestine U-shaped. Pterobranchs includes 2 orders, 3 genera and 20 species. Cephalodiscus, Rhabdopleura.
- 10. Balanoglossus
- 11. Cephalodiscus
- 12. • Subphylum II. Urochordata or Tunicata • (Gr. oura, a tail; L. chorda, cord). Notochord and nerve cord only in tadpole-like larva. Adult sac-like, • often sessile and encased in a protective tunic. Tunicates. • Class 1. Ascidiacea. Sessile tunicates with scattered muscles in tunic. Solitary, colonial or compound. Gill-clefts numerous. Ascidians or sea squirts. 2 subclass, 3 orders, 12 families, 37 genera and 1,200 species. Herdmania, Ciona, Molgula.
- 13. • Class 2. Thaliacea. Free-swimming or pelagic(marine) tunicates with circular muscles in tunic. Sometimes colonial. Salpas or chain tunicates. 3 orders, 5 families, 9 genera and 30 species. Salpa, Doliolum, Pyrosoma, • Class 3. Iarvacea or Appendicularia. Tiny, transparent, free- floating. Adults retain many larval features including tail. Only two -gill-slits. 2 orders, 2 families, 5 genera and 30 species. Oikopleura.
- 14. Subphylum III.- Acraniata The protochordate subphyla lack a head and a cranium, so that they are known as Acrania (Gr„ a absent; kranion,head). • Class I Cephalochordata (Gr. kephale, head; L. chorda, cord). Notochord and nerve cord present throughout life along entire length of body. • Body fish-like, segmented with distinct myotomes and numerous gill-slits. Free-swimming and burrowing. Lancelots. • One class, one family, 2 genera and 30 species. Branchiostoma (=Amphioxus), Asymmetron. About eight species have been recognized under the genus Branchiostoma and six species have been recognized from the genus Asymmetron.
- 15. Subphylum IV.- Craniata. On the other hand, the subphylum Vertebrata (subdivision Euchordata) has a distinct head and a cranium and is also called Craniata.
- 16. • Agnatha and Gnathostomata. The Vertebrata (or Craniata) are further subdivided in several ways. One possibility with universal agreement separates them into two unequal sections : Agnatha and Gnathostomata. Agnatha (Gr„ a, not; gnathos, jaw) lack true jaws and paired appendages. • Agnathans include a small number of primitive but highly specialized fish-like forms, the extinct ostracoderms and the modern cyclostomes • All other vertebrates have true jaws and paired appendages, and are called Gnathostomata (Gr., gnathos, jaw; stoma, mouth).
- 17. • Anamniota and Amniota. Another method of grouping the vertebrates elicits an extremely important advance in the pattern of embryological development. • It is based on the presence of a special membrane, the amnion, that holds the developing embryo in a reservoir of fluid, and permits the laying of eggs on land. • The animals that possess it belong to Amniota which includes the classes Reptilia, Aves and Mammalia. The animals without this membrane are Anamniota including cyclostomes, fishes and amphibians. Sometimes, the anamniotes are referred to as the lower vertebrates, and the amniotes as higher vertebrates.
- 19. REFERENCES • Modern Text Book of Zoology- Vertebrate (Animal Diversity II) By R. L Kotpal 11th Edition. Rastogi Publications.