Animal Classification

• Animal embryonic tissue layers

  • Endoderm
  • Mesoderm
  • Ectoderm
• Acoelomate animals


  Do not have a coelom (body cavity) produced during preadult development
• Pseudocoelomate animals


  Have a body cavity but it does not develop from splitting of the mesoderm embryonic tissue layer
• Coelomate animals


  Have a body cavity lined with mesoderm cells
• Protostomes


  Coelomates whose embryonic development makes a blastopore (first opening in the blastula) that later develops into a mouth
• Deuterostomes


  Coelomates whose embryonic development produces a blastopore that later forms an anus, with a second opening forming the mouth
• Segmentation allows animals to specialize certain segments, such as for antennae, eyes, claws, etc.
• Types of body symmetry

  • Asymmetrical
  • Radial
  • Bilateral
• Animals possess various body appendages like legs, tentacles and antennae that serve different functions