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Chordates (Phylum Chordata) Tunicates/Sea squirts (Urochordata) Lancelets (Cephalochordata)

Chordates (Phylum Chordata) Tunicates/Sea squirts (Urochordata) Lancelets (Cephalochordata) Vertebrates (Craniata - formerly vertebrata ). A. Characteristics 1. Notochord a. slender rod - provides axial support 2. Pharyngeal gill slits

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Chordates (Phylum Chordata) Tunicates/Sea squirts (Urochordata) Lancelets (Cephalochordata)

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  1. Chordates (Phylum Chordata) Tunicates/Sea squirts (Urochordata) Lancelets (Cephalochordata) Vertebrates (Craniata -formerly vertebrata)

  2. A. Characteristics 1. Notochord a. slender rod - provides axial support 2. Pharyngeal gill slits a. feeding in “primitive” chordates, became gills 3. Dorsal Hollow Nerve Cord (DHNC) a. fluid filled central canal above notochord b. solid and ventral in other invertebrates 4. Postanal Tail Dorsal, Hollow Nerve Cord Notochord Pharyngeal Slits Postanal Tail

  3. B. Tunicates(Subphylum Urochordata) 1. Sessile Marine animals 2. 2 life stages a. larval stage has chordate traits

  4. C. The lancelets (Subphylum Cephalochordata) 1. small (<5cm), fusiform, Marine organisms 2. Paedomorphosis a. juvenile morph is retained in reproductive adult b. retained larval form of Urochordates in reproductive adults Urochordate Larva Lancelet Adult

  5. C. Vertebrates 1. Subphylum Craniata a. formerly Vertebrata Phylogeny from

  6. 2. Vertebral Column a. Centrum - Bony vertebral column i. replaces notochord a. Neural Arch - encircles nerve cord - forms neural canal - some vertebrates lack vertebrae i. Hagfish-strengthend notochord 3. Cranium a. surrounds anterior brain - bone or cartilage Vertebra Cranium

  7. 4. Jawless Fishes (Superclass Agnatha) a. Hagfish(Class Myxini) - conatin most primitive characters - No vertebrae b. Lampreys(Class Cephalaspidomorphi) - Cartilagenous vertebral plates - Parasitic on other vertebrates Hagfish

  8. 5. Jawed Fishes (Superclass Gnathostoma) a. Jaws b. 2 sets of paired fins (Yaw, Pitch, roll) Modern Fishes Jawless Ancestors

  9. c. Cartilaginous fishes (Class Chondrichtyes) - Sharks and Rays - Cartilage skeleton - Multiple gill slits - Oil filled liver for buoyancy i. Also hydrodynamic lift

  10. - Reproduction i. Oviparous - lay eggs ii. Ovoviviparous - retain eggs internally until hatching iii. Viviparous - live bearing, nourishment from mother

  11. d. Bony Fishes (Class Osteichthyes) - Operculum - bony structure covering gills - swim bladder i. burp/gulp - connected to stomach - primitive ii. gas exchange - connected to blood vessels - derived

  12. - Ray-finned fishes(Actinopterygii) i. Extremely diverse ii. most of the fishes you know

  13. - Lobe-finned fishes (Sarcopterygii) i. Lungfish Live in shallow, fresh water Rely on lungs during dry season ii. Coelocanth Bottom dweller (off coast of Africa)

  14. e. Transition to Land

  15. f. Amphibians(Class Amphibia) - Salamanders, toads, frogs, caecillians -Moist skin i. adapted for cutaneous respiration - Oviparous i. Undergo metamorphosis

  16. g. Amniotes - Have amniotic egg i. shell that retains water - Can lay eggs in dry environments

  17. h. Turtles (Anapsids) - Shell - no temporal fenestra (anapsid) - oviparous

  18. i. Snakes and Lizards(Lepidosaurs) - Diapsid skull i. two fenestra (holes in temple) - Cranial kinesis (skull flexion) - scales

  19. j. Archosaurs - Crocodilians, Pterosaurs, Dinosaurs, Birds - Diapsid skull - Antorbital fenestra Archosaurs

  20. k. Birds (Class Aves)

  21. - Feathers i. Rachis and Barbs Rachis Barbs Rachis Barb

  22. - Bones (hollow, cross struts) - Keeled Sternum - Furcula (Wish bone) - Homeotherm i. constant body temperature ii. endothermy Furcula Bird in flight Keeled Sternum Flightless birds

  23. - Bill i. No teeth ii. Light keratin beak

  24. 6. Class Mammalia - Mammals

  25. 1. Synapsid skull a. 1 temporal opening

  26. 2. Hair - keratinized filaments

  27. 3. Mammary glands a. produce milk to nourish young b. derived from sweat glands

  28. - Heterodont dentition i. incisors - snipping ii. canines - tearing, grasping iii. cheek teeth - premolars - crunching - molars grinding or slicing

  29. - Limb position i. ventral - positioned under body - differs from lateral position in ancestors - Endothermy/Homeothermy

  30. - Monotremes - oviparous

  31. - Marsupials i. primitive placenta ii. altricial young

  32. - Eutherian mammals i. derived/advanced placenta ii. precocial young iii. most familiar mammals

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