2. Section 26-2 Section 26-3

4. Animal Characteristics Heterotrophs must ingest others for nutrients Multicellular complex bodies No cell walls allows active movement Sexual reproduction no alternation of generations no haploid gametophyte

5. Porifera Cnidaria Platyhelminthes spongesjellyfishflatworms roundworms Nematoda MolluscaArthropodaChordata AnnelidaEchinodermata mollusks multicellularity Ancestral Protist tissues bilateral symmetry body cavity segmentation Animal Evolution coelom starfishvertebrates endoskeleton segmented worms insects spiders notochord specialization &  body complexity specialized structure & function, muscle & nerve tissue distinct body plan; cephalization  body complexity  digestive & repro sys  digestive sys  body size redundancy, specialization,  mobility  body & brain size,  mobility radial bilateral Jointed appendages  mobility

6. Body Cavity ectoderm mesoderm endoderm ectoderm mesoderm endoderm mesoderm endoderm acoelomate pseudocoelomate coelomate coelom cavity pseudocoel Space for organ system development increase digestive & reproductive systems increase food capacity & digestion increase gamete production Coelem mesoderm & endoderm interact during development allows complex structures to develop in digestive system ex. stomach protostome vs. deuterostome

7. Early Embryonic Development ProtostomesDeuterostomes Gastrula Embryo Opening that forms first key

8. ProtostomesDeuterostomes Gastrula ( weeks) Embryo ( weeks) First opening Key to tissue layers