Lecture 19 - CILIA numerous short cellular appendages...

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BIOLOGY 1001: LECTURE 19 DIVERSIFICATION OF THE ANIMALS Major lineages appeared early in the history of animals; most major anatomical features have evolved repeatedly Large-scale classification of animals has been based on: 1.Symmetry: radial vs. bilateral 2.Gut: open vs. closed; if closed, whether lined with mesoderm ("coelomate") 3.Segmentation Taxon: example cnidarian: jellyfish, coral, anemones flatworms: planaria, flukes, tapeworms round worms: nematodes (e.g. Trichinella ) mollusks: snails, clams, octopus annelids: earthworms, polychaetes arthropods: centipedes, crabs, spiders, insects echinoderms: starfish Chordates: 1.Hemichordates: acorn worm 2.Urochordates: sea squirts 3.Cephalochordates: lancelets 4.Vertebrates: fish, amphibia, reptiles, mammals
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Unformatted text preview: CILIA - numerous short cellular appendages specialized for locomotion FLAGELLA - long cellular appendages specialized for locomotion (one per cell) COELOM - body cavity lined with mesoderm MESODERM - middle layer of early embryo that develops into the notochord, muscles, kidneys, heart NOTOCHORD - flexible rod located between the gut and the nerve cord SKELETONS: 1.Hydrostatic - fluid held in a closed body compartment that provides a rigid frame 2.Exoskeleton - hard encasement on the surface of an animal that provides points of muscle attachment 3.Endoskeleton - hard skeleton buried in the soft tissues of an animal. ANALOGY - similarity due to convergent evolution HOMOLOGY - similarity by common descent...
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