Phylum Platyhelminthes Phylum Annelida

 1. To know the features of flatworms  2. To know the characteristics of the three groups of flatworms

 Phylum Platyhelminthes  Physical characteristics:  Soft  Flat, only a few millimeters thick  Bilateral symmetry  Have a “head” region at anterior end  No circulatory or respiratory systems  Have nervous and excretory systems  Move by cilia or muscle cells  Can be free-living or parasitic

 Coelom – fluid filled body cavity  Acoelomates – organisms with no coelom  Flatworms are Acoelomates  Bilateral Symmetry – the animal has 2 well formed sides that can be identified as left and right (like humans).  Pharynx – muscular tube near mouth that flatworms extend out of their mouth to grab food and pump it to digestive cavity  Ganglia – group of nerve cells that are in the head region and control the nervous system  Eyespot – group of cells that look like eyes; can detect changes in the amount of light

 Sexual Reproduction  Hermaphrodites – an individual flatworm has both female and male reproductive organs  2 flatworms join in a pair and they both deliver sperm to each other  Eggs are laid  Asexual Reproduction  Fission – organism splits into 2 or more pieces and each part becomes a new organism

 1. Class Turbellaria (Turbellarians)  Free-living  Live in marine & fresh waters, also in muddy or sandy area on land  Hermaphrodites  Example: Planarian

 Class Trematoda (Flukes)  Parasitic, usually infect internal organs of host  Hermaphrodites, except Schistosoma  Ex: Schistosoma, a blood fluke

 Class Cestoda (Tapeworms)  Parasitic  Hermaphrodites  Body is segmented, made up of segments called proglottids  Ex: tapeworms

 1. To know the features of segmented worms  2. To know the characteristics of earthworms

 Phylum Annelida  Physical Characteristics  Segmented body  Have true coelom  2 openings, mouth and anus  Bilateral symmetry  Have Circulatory, respiratory, excretory, and nervous systems  Move by muscles or parapodia  Found on land and in water

 Sexual Reproduction  Some exhibit external fertilization and have separate sexes  Some are hermaphrodites  Usually, 2 worms attach to each other, exchange sperm  Clitellum secretes mucus ring where sperm and eggs are released to fertilize  Ring slips off and forms protective cocoon until baby worms hatch

 Septa – internal walls in between each segment  Setae – bristles attached to segments  Closed Circulatory System – where blood is contained in a network of blood vessels  Gill – organ that exchanges oxygen and carbon dioxide underwater  Clitellum – band of thick, specialized segments that are important in reproduction

 Class Oligochaeta  Found in soil  Make Castings, undigested part of soil that exits as waste  Few setae