1. Phylum Chordata SBI 3U

2. What are Chordates?  Chordates are animals with a nerve cord, notochord and gill slits (at least at some point in their lives)

3. Characteristics of Chordates  Bilaterally symmetrical  Ventral heart  Body extends past anus into a tail  Nerve cord  Notochord  Gill slits

4. More about chordates  Most recent group of animals  Make up only about 5% of animal species

5. What is a nerve cord?  Unique to chordates  Dorsal nerve cord (dorsal=back side)  Found in the embryos of animals within the phylum chordata  NOT the spinal cord  but it develops into one in vertebrates  Part of the nervous system  Connects the brain with the lateral muscles and other organs

6. What is a notochord?  A notochord is a skeletal rod made up of cartilage  Found in all embryonic and some adult chordates  In vertebrates  only present during embryonic development

7. Classification of Chordates  Three subphyla: Cephalochordata, Urochordata and Vertebrata  Cephalochordata: such as lancelets  Urochordata: such as tunicates  Vertebrata: such as amphibians, reptiles, birds and mammals

8. Cephalochorata & Urochordata  Filter-feeding marine organisms  Filter-feeding  pass water over a specialized filtering structure  Have notochords  No backbones or vertebral columns  Transition from invertebrates  chordates  Example: Lancelet (cephalochordata)  Example: Tunicate

9. Vertebrata  Approx. 95% of all chordates  Presence of vertebrae  hollow, cartilaginous, bony structure  protects dorsal nerve cord  Endoskeleton  Large brain protected by skull  Advanced nervous system  Circulatory system  Large coelom  containing vital organs

10. Development of Appendages  Two pairs of appendages  limbs  Improvement of locomotion  One of the defining features of vertebrates  Even snakes have them!

11. Skull  Anterior skull with a large brain  Supports structures of the face and protects brain MouseHuman Dog

12. Circulatory System  Ventral heart  pumps blood throughout body  in the process, delivering oxygen throughout