Earthworm Vocabulary for Dissection *copy these words in your folder and define for homework. These are the structures that you will need to know the function and location for during the dissection

sperm ducts prostomium setae dorsal blood vessel ventral blood vessel Closed circulatory system mouth anus clitellum DORSAL side Cerebral Ganglia Nephridia Ventral nerve cord

septa seminal vesicles Seminal receptacles aortic arches Crop Mouth Pharynx Intestine Gizzard Anus Esophagus Pharyngeal Muscles

External anatomy of an earthworm

External cont…..

External Structures of the Worm 1 Mouth 2 Prostomium 3 Segment 4 Spermathecal openings 5 Female (oviduct) opening 6 Male (vas deferens) opening 7 Sperm groove 8 Papilla 9 Clitellum (saddle) 10 Paired setae (ventro-lateral) 11 Anus 12 Dorsal surface 13 Ventral surface

Dissection Guidelines: Internal Anatomy 1. Place the specimen in the dissecting pan DORSAL side up 2. Locate the clitellum and insert the tip of the scissors about 3 cm posterior. 3. Cut carefully all the way up to the head. Try to keep the scissors pointed up, and only cut through the skin. 4. Spread the skin of the worm out, use a teasing needle to gently tear the septa (little thread like structures that hold the skin to organs below it) 5. Place pins in the skin to hold it apart,

Internal view of earthworm

1 Anus 2 Intestine 3 Cerebral ganglion 4 Prostomium 5 Mouth 6 Nerve collar 7 Segmental ganglion 8 Pharynx 9 Esophagus 10 Segmental nerve 11 Crop 12 Gizzard 13 Ventral nerve cord

1 Anus 2 Dorso-subneural vessel 3 Intestine 4 Dorsal vessel 5 Hearts (aortic arches) 6 Mouth 7 Ventral vessel 8 Subneural vessel

Reproduction in earthworms