Kingdom Animalia Lower Invertebrates Characteristics eukaryotic multicellular heterotrophic

Kingdom Animalia Lower Invertebrates

Characteristics: • • eukaryotic multicellular heterotrophic consumers no cell walls sexual and asexual reproduction locomotion 99% invertebrates

• symmetry of body plan: asymmetry – no symmetry radial – central point; can be divided into equal sections bilateral – can be divided into 2 mirrored halves • cephalization – concentration of sense organs toward anterior end (associated with development of a head)

• anterior – region of a bilaterally symmetrical organism toward the head end • posterior – region of a bilaterally symmetrical organism toward the tail end • dorsal – back side of a bilaterally symmetrical organism • ventral – under side of a bilaterally symmetrical organism • lateral – to the side of a bilaterally symmetrical organism

A. Phylum Porifera • sponges • simplest animals • adults sessile, filter feeders (larvae are freeswimming) • water vascular system – pumps large amts. of water through porous body; all aquatic • asymmetrical

A. Phylum Porifera • • composed of spicules – framework of the sponge classified by spicule composition: reproduce sexually by egg and sperm asexually by budding

B. Phylum Cnidaria • • • corals, jellyfish, anemones radial symmetry entirely aquatic (marine, few fw) possess stinging cells (nematocysts) on tentacles nerve net – simple nervous system

B. Phylum Cnidaria • classified by life cycle stages: 1) medusa – free swimming 2) polyp – attached stage • reproduction: asexually by budding sexually by egg & sperm

C. Phylum Platyhelminthes • flatworms • incomplete digestive system (one opening) • bilateral symmetry

D. Phylum Nematoda • • • roundworms complete digestive system – 2 openings bilateral symmetry tube within a tube body plan ex: Ascaris, hookworms, filarial worms, eyeworms, Trichinella – cause trichinosis

E. Phylum Annelida • • • segmented worms name means “little ring” true coelom – fluid-filled body cavity complete digestive system all organ systems present closed circulatory system – blood is confined to vessels

E. Phylum Annelida • classified by their number of setae – bristles for locomotion