CHAPTER 30

• Kingdom Animalia


  • Multicellular
  • Ingestive heterotrophs
• Domains and Kingdoms


  • Bacteria
  • Archaea
  • Amoebozoa
  • Opisthokonta
  • Fungi
  • Choanoflagellates
  • Eukaryotes
  • Animals
  • Excavata
  • Algae
  • Land plants
  • Protists
  • Rhizaria
  • Alveolata
  • Stramenopila
• Choanoflagellates and Sponge Feeding Cells Are Almost Identical in Structure and Function
• Animal Architecture


  • Level of development
  • Number of embryonic tissue types
  • Type of body symmetry
  • Presence of a body cavity
  • Embryonic development
• Cellular Level


  Cells separated can survive and reaggregate
• Tissue Level


  Cells rely on each other for their function and survival
• Organ Level


  Two or more tissues bundled together into a discrete structure (each contributing its part to the function of the organ)
• Organ System Level


  Two or more organs work together as a system (teamwork = efficiency)
• Sponges are at the cellular level of development
• Diploblasts


  • Have 2 embryonic tissue types (Cnidaria & Ctenophora)
• Triploblasts


  • Mesoderm forms in the blastocoel after the infolding of the endoderm
  • Ectoderm: skin, nervous system
  • Mesoderm: most internal organs, skeletal muscle
  • Endoderm: digestive tube
• Most animals are triploblastic
• Symmetry


  The ability to split something into mirror images
• Radial symmetry


  • Can be split into mirror images in > 1 plane
  • Symmetry radiates out from the center
  • Radial symmetry is an adaptation for sessile filter feeding
• Bilateral symmetry


  • Can be split into mirror images in only 1 plane (right side and left side)
  • One way directional movement
  • Cephalization (most senses out front)
• Bilateral symmetry in sea anemones is homologous to bilateral symmetry in bilaterians
• Determining if bilateral symmetry in sea anemones is homologous to bilaterians

  1. Stain gene products (proteins) of Hox gene in developing Nematostella embryos and larvae to reveal location of expression

  2. Repeat for other Hox and dpp gene products
• The genetic determination of bilateral symmetry has deep homology in Nematostella and bilaterians
• Nerve net


  Diffuse neurons in hydra
• Central nervous system


  Clustered neurons in earthworm
• The Tube-within-a-Tube Body Plan Is Common in Animals
• Coelomates


  Have an enclosed body cavity completely lined with mesoderm
• Acoelomates


  Have no enclosed body cavity
• Pseudocoelomates


  Have an enclosed body cavity partially lined with mesoderm
• Earthworm nervous system


  • Clustered neurons
  • Cerebral ganglion (brain)
  • Ganglia (radial, bilateral)
• Skin and nervous system derived from ectoderm
• Muscles and organs derived from mesoderm
• Coelom (cavity lined with mesoderm)
• Gut derived from endoderm
• Tube-within-a-Tube Body Plan


  • Inner tube
  • Outer tube
  • Complete digestive system

  
• Coelomates


  • Enclosed body cavity completely lined with mesoderm
  • Increased gas exchange
  • Less restriction in movement
  • Shock absorptive (coelomic fluid)
• Acoelomates


  • No enclosed body cavity
  • Limited gas exchange
  • Restrictive
  • No shock absorption
• Pseudocoelomates


  • Enclosed body cavity partially lined with mesoderm
  • Same benefits as the coelom
• Gastrulation


  Formation of gut and embryonic germ layers
• Protostomes


  Blastopore becomes mouth
• Deuterostomes


  Blastopore becomes anus
• Formation of coelom


  1. Mesoderm pockets pinch off of gut to form coelom (enterocoely)

  2. Blocks of solid mesoderm split to form coelom (schizocoely)
• The protostomes and deuterostomes represent the 2 groups of bilateral animals
• The diversity seen within a taxonomic group (i.e. a Phylum) is usually related to specializations for feeding or locomotion
• Arthropod, Onychophoran, Annelid


  • Developing legs
  • Developing segments