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 free- swimming) 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

Earthworm prostomium – liplike covering over mouth; pushes soil into mouth clitellum – banded structure that functions in reproduction by secreting a mucus ring which carries fertilized eggs and is left behind as a cocoon reproductive system: hermaphrodite – has both male & female sex organs ovaries – produce eggs testes – produce sperm seminal vesicles – store worm’s own sperm seminal receptacles – receive other worm’s sperm

Earthworm digestive system: complete (mouth & anus) mouth – takes in food pharynx – sucks in soil esophagus – transports food to crop crop – stores food gizzard – grinds food intestine – absorbs nutrients anus – releases wastes

Earthworm circulatory system: closed; will be black no heart; has aortic arches (pump blood) dorsal blood vessel – carries blood to aortic arches ventral blood vessel – carries blood to posterior end respiratory system: O 2 & CO 2 (gases) exchanged through moist skin; kept moist by secreting mucus

Earthworm excretory system: nephridia – “little kidneys” remove wastes from blood cuticle – outer skin-like covering on worm that secretes mucus nervous system: fused nerve cells (ganglia) simple brain that sends/receives messages ventral nerve cord – carries messages to/from body from/to ganglia