intro

• Common Characteristics of KINGDOM ANIMALIA

  • Eukaryotic
  • Multicellular
  • No Cell Wall
  • Heterotrophic
  • Motile
• Historically, protozoan were regarded as one-celled animals
• protozoans often possessed motility and predation and lack a cell wall
• Protozoa - Unicellular, , no division of labor as the as the single cell performs all biological functions.
• Metazoa - Multicellular, shows division of labor
• Classification is a method of classifying or organizing something according to shared qualities or characteristics.
• we can classify animals based on the following:

  1) anatomy;

  2) morphology;

  3) evolutionary history;

  4) features of embryological development; and 5) genetic makeup.
• The animal kingdom is divided into Parazoa (sponges and placozoans) and Eumetazoa (all other animals)
• PARAZOA (“beside animal”) do not do not contain true specialized tissues
• Although organisms in group PARAZOA do possess specialized cells that perform different functions, those cells have no grouping and coordination of the body cells to form the tissues
• Animals with true tissues are in the group EUMETAZOA (“true animals”)
• Different types of tissues in eumetazoans are responsible for carrying out specific functions
• This differentiation (in EUMETAZOA) and specialization of tissues contribute to animal diversity
• For example, the evolution of nerve and muscle tissues has resulted in animals' unique ability to sense and respond to changes in their environment.