BIOL 1002 Chapter : BIOL 2
Document Summary
Chapter 23: animal diversity i: invertebrates2/13/2012 7:10:00 pm. Include: appearance of tissues, appearance of body symmetry. Lack of tissues separates sponges from all other animals. Tissues - groups of similar cells that carry out specific function. Sponges = only modern-day animals lacking tissues. Individual cells in sponges may be specialized, but act independently & aren"t organized into true tissues: animals with tissues exhibit either radial or bilateral symmetry. Symmetrical animals have upper (dorsal) surface & lower (ventral) surface. Symmetrical animals are divided into 2 groups: What are the major animal phyla: animals probably originated from ancestral protists. Present day biologists recognize about 27 phyla of animals: most animals are invertebrates - lack a vertebral column. Less than 3% of all known animals are vertebrates - possess a vertebral column: phylum porifera, sponges have a simple body plan, sponges belong to phylum porifera & found in most marine environments.
