Body Plans and Adaptations

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Body Plans and Adaptations
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Symmetry Shape and balance in proportions of the
organism

• Asymmetry without symmetry, no pattern to the
  body plan. Body is randomly shaped. Examples
  sponges
• Radial Symmetry Can be divided along any plane
  through a central point. Like slicing a pie.
  Example hydra, starfish
• Bilateral Symmetry Can be divided down the
  middle into two almost equal mirror images.
  Example Butterfly, humans

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Anatomical terms

• Anterior head end
• Posterior tail end
• Dorsal back surface
• Ventral belly surface

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Coeloms

• Acoelomate has ectoderm, mesoderm, and endoderm
  but no coelom or body cavity Example flatworms
• Pseudocoelomate has the three layers and a fluid
  filled body cavity partially lined with mesoderm.
  Example roundworm
• Coelomate Has a fluid filled space completely
  surrounded by mesoderm. This is where we see the
  greatest diversity in body plans. Examples
  Humans, fish, earthworms, insects

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Image taken from http//www.sidwell.edu/us/science
/vlb5/Labs/Classification_Lab/pics/coelom.jpg
Image taken from http//www.ptpleasantbch.k12.nj.u
s/bridge/genbio/bioimages/psuedocoelom.jpg
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Body Support

• Exoskeleton A hard waxy covering on the outside
  of the body. Protect soft body tissues and
  prevent water loss. Growth is limited because
  they must shed the exoskeleton. This leaves them
  vulnerable for part of their life. Mainly found
  in invertebrates animals without a backbone.
• Endoskeleton Internal framework of cartilage and
  bone that provides structure. Does not have to
  be shed to grow. Mainly found in Vertebrates
  Animals with backbones. Echinoderms (starfish
  are the exception. They are invertebrates with
  an endoskeleton.