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

http://images.google.com/imgres?imgurl=http://www.okc.cc.ok.us/biologylabs/Images/Porifera_Cnidaria/sponge%2520copy.JPG&imgrefurl=http://www.okc.cc.ok.us/biologylabs/Documents/Porifera_Cnidaria/Porifera.htm&h=332&w=450&sz=29&tbnid=t5jNolvgK2sJ:&tbnh=91&tbnw=123&hl=en&start=6&prev=/images%3Fq%3Dporifera%26hl%3Den%26lr%3D%26sa%3DG

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

http://images.google.com/imgres?imgurl=http://www.medizin.uni-tuebingen.de/~webitm/dracunculus.jpg&imgrefurl=http://www.medizin.uni-tuebingen.de/~webitm/doktorar.html&h=297&w=213&sz=10&tbnid=s6IrHceaUoEJ:&tbnh=110&tbnw=79&hl=en&start=5&prev=/images%3Fq%3D%2BDracunculus%2Bmedinensis%26hl%3Den%26lr%3D%26sa%3DG

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

http://images.google.com/imgres?imgurl=http://www.schools.pinellas.k12.fl.us/gallery/variety/Snail.gif&imgrefurl=http://www.schools.pinellas.k12.fl.us/gallery/variety/Page0008.html&h=216&w=217&sz=10&tbnid=6EnUbUAdMxQJ:&tbnh=100&tbnw=100&hl=en&start=3&prev=/images%3Fq%3Dsnail%26hl%3Den%26lr%3D%26sa%3DG

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