Invertebrate symmetry+segmentation

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Biological diversity - invertebrate symmetry+segmentation

  • eukaryotic
    • cells - organelles, nucleus containing genetic material+no chloroplasts
    • lack rigid cell walls
    • store carbohydrates - glycogen
  • multicellular
    • body cells - arranged - form tissues eg nervous system
    • tissues - arranged - form organ systems eg vascular system
  • diploid
    • body cells - contain duplictae chromosomes
  • heterotrophic
    • must obtain enery+carbon - ingesting other animals/absorbing nutrients - environment
  • aerobic respiration 
    • requires oxygen
  • reproduction
    • sexual+asexual
  • embryonic cells
    • ectoderm
    • endoderm 
    • mesoderm
  • life cycle
    • motile - part lif cycle
    • stages - embryonic development, mitotic division transforms cell - multicellular embryo 
  • growth, survival+reproduction+(disperal+sexual reproduction)
  • sponges (complex multicellularity)
  • Cnidarians - distinct tissues
  • Platyhelmids - high levels - tissue specialisation 
  • roundworms - body cavity 
  • insects
  • organisms - true comple multicellularity:
  • Parazoans (sponges)
  • true multicellularity - not tissue development 
  • lack symmetry 
  • larval stage = free swimming
  • adults = sessile
  • distinct tissues alter life cycle - organism?
  • animals - sub-kingdom eumetazoa, sub-group radiata, phylum cnidaria
  • 4 classes: hydroids, sea anemones, jellyfish+corals
  • inner endoderm+outer ectoderm formed - embryo
  • 2 body forms - Cnidarians = polyp - medusa
  • class Scyphozoa = jellyfish
  • class Hydrozoa = hydroids
  • both medusa+hydroid stages - life cycle
  • most = marine+colonial
  • well known hydroid = freshwater genus hydra - no medusa stage (exception)
  • class Anthozoa = corals
  • secrete exoskeletons - calcium carbonate
  • form coral reefs - nutrient poor water - abundant algae found there
  • fertilised eggs develop - planulae - settle into polyps, no medusa formed
  • Anthoza includes se anemones
  • plant like body, topped - tuft hollow tentacles 
  • harbour symbiotic algae
  • highly muscular 
  • retract - touched
  • kingdom - Animalia
  • phylum (division)
    • 30+ phyla (how divide them)
    • based - body plan/ genetic relationship
  • invertebrates
    • no back bone
    • Circa 2 million species
  • vertebrates
    • mammals, birds, reptiles, fish+amphibians
    • 50000+ species
  • Animalia
    • body symmetry
    • cephalisation
    • type - gut
    • type - body cavity
    • segmentation
  • Parazoans - simple multicellular animals lacking body tissues
  • Eumetazoans
    • radial symmetry - 2 layers tissue
    • bilateral symmetry - 3 layers tissue
  • sponges:
    • no symmetry 
    • no tissues
    • no organs
    • tubular - not symmetrical 
    • variable shape 
    • very successful
  • Cnidarians:
    • radial symmetry 

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