ABBOTTSCOLLEGE

1. ANIMAL KINGDOM PHYLUM CHORDATA Page 81 ABBOTTSCOLLEGE

2. Animals that have a backbone • Most advanced type of animal

3. An extremely successful group of animals • Occupy a wide range of habitats • Have: • Bilateral symmetry • Cephalisation • Triploblastic tissue layers • Segmented body • Well developed coelom • Through gut

4. All chordates have: • Notochord • Hollow, dorsal, tubular nerve cord • Pharyngeal (gill) slits • Post-anal tail PAGE 81

5. Rod-like support • Present in basic and developing chordates • Normally replaced later in life by the vertebral column • First type of backbone support in evolution

6. Beginnings of a spinal chord • Forms the brain at one end • Remains present, but becomes modified in most chordates

7. Appear in development of all chordates • Disappear in terrestrial animals • Remain present in fish

8. A muscular structure that extends beyond the anus. • This may remain present all through life, but often disappears as the animal matures.

9. Phylum includes over 43 000 species • 3 Subphyla • Subphylum Urochordata • e.g. Sea Squirts • Subphylum Cephalochordata • e.g. Amphioxis • Subphylum Vertebrata • e.g. Fish, birds, mammals, reptiles and amphibia The first two subphyla are made up of A very few primitive aquatic marine forms Do not have vertebrae

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