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