animal diversity overview

• Characteristics of animals


  • Eukaryotic
  • Multicellular
  • Cells lack cell walls
  • Heterotrophic
  • Sexual reproduction (mostly)
  • Diverse and complex developmental strategies (Gastrulation, Symmetry, Multiple tissue layers, Larval stage(s))
• Animals: reproduction and development
• Animal phylogeny: 'body plans'


  • Combine morphological, molecular, and fossil data
  • Approximately 35 animal phyla
  • Body plan: set of morphological and developmental traits (Groups of animals can be differentiated based on body plans, e.g. symmetry, tissues, body cavities)
• Animal body plans: symmetry


  • Radial symmetry; diploblastic
  • Bilateral symmetry; triploblastic

  
• Animal body plans can be traced back to embryonic development
• Animal body plans: tissues


  • Animal embryos develop from 2 (diploblastic) or 3 (triploblastic) primary (germ) tissue layers; formed during gastrulation (Ectoderm, Endoderm, Mesoderm)

  
• Animal body plans: body cavities (coelom)

  • Acoelomate, Coelomate, Pseudocoelomate
• Animal body plans: protostomy (first mouth) vs. deuterostomy (second mouth)


  • Protostomes, Deuterostomes
• Hypothetical animal phylogeny
• Animal phylogenies: general points of agreement


  • All animals share a common ancestor

  Sponges are basal animals

  Eumetazoa is a clade of animals with true tissues

  Most animals are Bilaterians (belong to the clade Bilateria)

  There are three major clades of Bilaterians (Deuterostomia, Ecdysozoa and Lophotrochozoa)