ECON 2010 Lecture 8: Section 8B - Vertebrates
3 Apr 2016
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Kingdom animalia, part b the vertebrates 1 the major classes of vertebrates. Characteristics that distinguish them from invertebrate chordates (tunicates and lancelets) Cranium: protective bony or cartilaginous housing for brain. Neural crest: embryonic cells found on either side of the neural tube as it develops disperse throughout the embryo contributing to the development of the skeleton, nerves, jaws, teeth. Additional characteristics include having 2+ clusters of hox genes allowed more complex morphologies. Vertebral column - notochord is replaced by a bony or cartilaginous column of interlocking vertebrae. Endoskeleton of cartilage or bone strong, but flexible. Contains living cells that secrete the skeleton, which grows with the animal. Most have 2 pairs of appendages (fins, legs, arms) Internal organs including liver, kidneys, endocrine glands, and a heart with at least two chambers. Heart, kidneys, and endocrine system are more complex. 11 classes 5 are fish: ~25,000 species. Ostracoderms: term for several classes of early diverging, heavily armoured fish (now extinct)
