Biology 242: Lecture 4Spring 2001

Invertebrates III/Introduction to Chordates

  1. Phylum Echinodermata
    1. Characteristics
      1. Water vascular system
      2. Tube feet
      3. Bony endoskeleton
    2. Major groups
      1. Class Asteroidea = sea stars
      2. Class Ophiuroidea = brittle stars
      3. Class Echinoidea = sea urchins, sand dollars
      4. Class Crinoidea = sea lilies
      5. Class Holothuroidea = sea cucumbers

  2. Phylum Chordata
    1. Characteristics
      1. Notochord
      2. Dorsal, hollow nerve cord
      3. Pharyngeal slits
      4. Muscular postanal tail
    2. Major groups
      1. Subphylum Urochordata = tunicates (sea squirts)
      2. Subphylum Cephalochordata = lancelets
      3. Subphylum Vertebrata

  3. Origin and diversification of animals
    1. Origin
      1. Syncytial hypothesis
      2. Colonial hypothesis
    2. Diversification - Cambrian explosion (545 mya)


"No pain, no gain...no difficulties, no discoveries."
Apples of Gold