Shared Animal Characteristics Multicellular Most have tissues and organs Aerobic heterotrophs Reproduce sexually Develop from embryos Motile Today we will focus on invertebrates No internal backbone Compare similarities and differences through several basic features
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Shared Animal Characteristics
Multicellular Most have tissues and organs
Aerobic heterotrophsReproduce sexuallyDevelop from embryosMotileToday we will focus on invertebrates
No internal backboneCompare similarities and differences
through several basic features
Symmetry
Radial symmetry: body parts arranged around a central axis
Bilateral symmetry: have a front and back end and right and left side
Embryo Tissue Layers
Zygote develops into a mass of cellsPrimary tissue layers form
Simple radial animals have two layers Outer ectoderm Inner endoderm
Bilateral animals have a third layer, mesoderm in the middle
Pattern of Development
Protostome: first embryo opening becomes the mouth Examples: flatworms, molluscs, roundworms,
arthropods
Deuterostome: second embryo opening becomes the mouth Example: Echinoderms, chordates
Body cavity: Coelom
Cavity between the gut and the wall that is lined with tissue Cushions organs Helps organs grow and move independently
No true tissuesNo germ layersAcoelomatesNo symmetrySessile adultAsexual and sexual reproductionSpicules: made of different substances; for protectionCollar cells (choanocytes)-flagellated, create water
currentsAmoebocytes-digestion, secretionEpidermal cells-cover surfaceOsculum: largest opening for water