Chapter 32 Animal Classification

Characteristics of Animals Multicellular, heterotrophic eukaryotes Lack cell walls (held by collagen in ECM), have tight and gap junctions and desmosomes Have nervous and muscle tissue Most reproduce sexually; dominant diploid stage, zygote undergoes cleavage to form blastula (leads to gastrulation)

Animal Phylogeny

Tissue ____________: lack true tissue All other animals are eumotozoa: have tissue

Radial Vs. Bilateral Symmetry Radial: Cnidaria and Ctenophora All others: bilateral, have dorsal, ventral, anterior and posterior sides – Cephalization: sensory equipment toward ___________________ end – Germ layers of development: add mesoderm between endoderm and ectoderm (tripoblastic)

Body Cavity Acolemates (_________________) lack a body cavity, true digestive and circulatory system Pseudocoelomates: cavity not completely lined by tissue Ex. Phylum Rotifera and Nematoda Coelomates: Body cavity lined by tissue

Protostomes versus Deuterostomes ProtostomesDeuterostomes Examples Cleavage CoelomSchizocoelus development:Enterocoelus development: Blastopore