Chapter 9. Multicellular and Tissue Levels of Organization. Evolutionary Perspective. Porifera No tissues Division of labor among independent cells Independent origin from common animal ancestor Choanoflagellate protists (?) Cnidaria and Ctenophora Tissue level organization
Multicellular and Tissue Levels of Organization
Figure 9.1 Evolutionary relationships of the Porifera, Cnidaria, and Ctenophora.
Figure 9.2 Two hypotheses regarding the origin of multicellularity. (a) Colonial hypothesis. (b) Syncytial hypothesis.
(b) Amphiblastula larva.
Figure 9.10 The generalized cnidarian life cycle involves alternation between a sexual medusa stage and an asexual polyp stage.
Figure 9.12 Gonionemus medusa. The velum is unique to members of the Hydrozoa.
Figure 9.13 Members of the class Staurozoa are marine and lack a medusa stage. Lucernaria janetae is shown here.
Figure 9.14 Representative scyphozoans (a) Mastigias qinquecirrha and (b) Aurelia labiata.
Figure 9.17 The sea wasp, Chironex fleckeri.
Figure 9.18 (a) The giant sea anemone (Anthopleura xanthogrammica) and (b) a sea anemone (Callictis parasitical)
living in a mutualistic relationship with a hermit crab.
Figure 9.21 Octacorallian corals (a) Ptilosaurus gurneyi and (b) Gorgonia ventalina.
Figure 9.22 (a) The bioluminescent ctenophoran Mnemiopsis sp. (b) The structure of Pleurobranchia. (c) Colloblast structure.