Earthworm Lab Preview April 16, 2012

 General Terms for an Animal’s Structure:  Dorsal – top side  Ventral – bottom side  Anterior – front of the earthworm; where the mouth is located.  Posterior – back end; where the anus is located. Anterior Ventral Dorsal Anterior Dorsal Ventral Posterior

 Earthworm External Features:  Segments – sections of the body  Clitellum – smooth band around the earthworm that forms a cocoon for fertilized eggs during reproduction.  Setae – bristles found along the ventral side of the earthworm that help it move.  Mouth – takes in food; closer to clitellum; anterior end of worm.  Anus – releases wastes; posterior end of worm. Segment Clitellum Mouth Anus Setae

 Earthworm Body Systems  Circulatory System – How the blood circulates through the body.  Aortic Arches (hearts) – pumps blood.  Blood Vessels – both dorsal and ventral sides of worm. Circulatory System in RED

 Earthworm Body Systems  Nervous System – How the worm senses and feels things.  Brain – very difficult to see; near segment 2.  Nerve Cord – only on ventral side of worm. Nervous System in YELLOW

 Earthworm Body Systems  Reproductive System – Making more earthworms.  Clitellum – holds fertilized eggs.  Seminal Vessicles – sperm is made here.  Seminal receptacles – sperm is stored here. Earthworms are hermaphrodites meaning they have both male and female structures. Clitellum Seminal Vesicles and receptacles

 Earthworm Body Systems  Digestive System – Taking in food and breaking it down.  Mouth – takes in food; anterior end.  Pharynx – muscular tube leading to the esophagus.  Esophagus – tube going from the pharynx to the crop.  Crop – stores food.  Gizzard – grinds food.  Intestine – main organ in digestion.  Anus – releases wastes. Digestive System in GREEN

 Earthworm Body Systems  Excretory System – Gets rid of wastes.  Nephridia – little coiled tubes that get ride of wastes throughout the worm.  Anus – releases wastes. Anus