Animals:  Porifera, Cnidaria, Ctenophora



  1. Multicellular eukaryotes: cells are specialized (division of labor) to form tissues and organs (except for the most primitive)
  2. heterotrophic (consumers): ingest food; digest internally, usually in a digestive system
  3. locomotion - during at least some part of the life cycle (many have sessile adult stages) and motion: by means of contracting fibers
  4. diplontic life cycle (diploid adult)
  5. sexual reproduction producing sperm and eggs; some asexual; embryo undergoes stages of development


(image courtesy of BIODIDAC)

Sponges, 9,000+ species. [fig. 18.4]

Types of Canal Systems [fig. 18.7]

  1. Asconoids: image at right courtesy of BIODIDAC)
  2. Syconoids:
  3. Leuconoids:
    • increased surface area to volume ratio


Sponge Classification [Table 18.1]

  1. Class Calcarea-Clathrina from UW La Crosse
  2. Class Hexactinellida- glass sponges
  3. Class Demospongea- 90% of all sponges, such as this yellow barrel sponge


EUMETAZOA: tissues and organs present:

  1. radiata: radial symmetry, diploblastic - Cnidaria and Ctenophora
  2. bilateria - the rest of the animal kingdom



  • morphology
    1. radial symmetry or modified biradial
    2. polyp and medusa body forms - tentacles around oral end [Fig. 18.11]
    3. diploblastic
      1. epidermis and gastrodermis [Fig.18.9]
      2. mesoglea
      3. muscle tissue
    4. tissue level of organization
    5. sac body plan
    6. gastrovascular cavity
    7. hydrostatic skeleton
    8. cnidocytes: cells with nematocysts [fig. 18.10]
    9. nerve net
    10. statocysts
  • sexual reproduction by gametes and asexual budding;
    • "alternation of generations" [Fig. 18.11]

    images to right courtesy of BIODIDAC


polyp (sea anemone, Class Anthozoa), showing modified radial symmetry

Scyphozoa-Diagram of the life cycle of Aurelia 

Classification [Table 18.2]

  1. Hydrozoans
  2. Scythozoans
    • jellyfish [Fig. 18.14-18.15]
    • characteristics-link to the Woods Hole Marine Biological Laboratory
    • life history and reproduction [Fig. 18.16]
    • Mastigias [Fig. 18.14a]
    • Aurelia
  3. Cubozoans
    • morphology
    • sea wasps [Fig. 18.17] - Chironex
  4. Anthozoans


Obelia - polyp and medusae


images courtesy of BIODIDAC


Learn about comb jellies [Fig. 18.22] 




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