Invertebrate Overview

Body Symmetry Radial Symmetry-body parts that repeat around center body-Cnidaria and Echinodermata Bilateral Symmetry-imaginary plane divides animal into to equal parts-Platylhelminthes,Nematoda,Annelida,Mollusks,Arthropoda Asymmetrical-no front back or sides-Porifera

Radial Symmetry

Bilateral-

Phylum Porifera Pores all over the body Multicellular Heterotrophic No cell walls Coanocytes-specialized cells that use flagella to move water through Spicules-in some sponges and is a hard-skeleton – like substance No particular nervous system Reproduction is internal fertilization,larvae released into water Gemmules-layer of archaeocytes surrounded by spicules—asexual budding under harsh conditions

asymmetrical

Cnidaria Hydra,jellyfish,corals,sea anemones 1)Class Scyphozoa-jellyfish-reproduce sexually/seen mostly as medusa 2)Class hydrozoas-hydras(fresh water),Portugese-Man-of-War-mostly in polyp stage 3)class Anthozoa-sea anemone and corals-only polyp stage-reproduce asexually by releasing eggs and sperm into water/some can reproduce asexually

Reproduce externally 2 stages-polyp and medusa Stinging cells-nematocysts

Platylhelminthes Flatworms Flukes,planaria and tapeworms 3 classes: 1)turbellaria-planaria/ 2)Trematoda- flukes-parasitic/ 3)cestoda Hermaphrodites that reproduce sexually Regeneration

Nematoda Some are parasitic Reproduce sexually and usually have separate sexes Parasitic varieties include ones causing trichinosis,filarial,ascarid and hookworms Sexual reproduction,other systems have also made advances

Phylum Annelida Class Oligochaetes-earthworms Class Hirudinea-leeches Class Polychaetes-sandworms and bloodworms Most reproduce sexually 2 major groups of muscles Nephridia

Phylum Mollusca Soft-bodied animals that usually have an external or external shell Body usually has 4 parts-foot,mantle,shell and visceral mass 1)class Gastropoda-snails and slugs/shell-less or single shell/muscular foot 2) Bivalves-2 shells held by muscle…clams,etc. 3) Cephalopods-soft bodied w/tentacles—octupi and squids

Phlum Arthropoda Insects,crabs,lobsters,shrimp,spiders All have a tough exoskeleton 1)subphylum-Crustacea-attenae,3 body sections,chewing mandibles/crayfish,etc, 2)subphlum chelicerata-horseshoe crabs,spiders,ticks,scorpions-2 body sections and 4 pairs of walking legs 3) subphylum Uniramians-1pair attenae and unbranched appendages-insects