Earthworm Dissection

Lumbricus terrestrisKingdom: AnimaliaPhylum: Annelida

Students should identify the following

• Segments• Septum• Setae• Pharynx• Esophagus• Crop• Gizzard• Intestine• Aortic Arches (Hearts)• Ventral Nerve Cord

• Dorsal Blood Vessel• Clitellum• Seminal Vesicles• Seminal Receptacles• Cerebral Ganglion (brain)• Anus• Mouth

Students should know the following terminology

• Invertebrate• Castings• Hermaphroditic• Hydrostatic Skeleton• Closed Circulatory System

Before you start dissecting, find the following:

• Mouth• Setae – the bristles used for locomotion. They

are located by rubbing your fingers along the earthworm’s body. They are often times easier to feel than to see.

• Sperm Duct• Clittelum

Mouth

Sperm Duct

Clittelum

Mouth

Pin your worm at the tip of the mouth and at its anus.

Start your incision 2 cm behind the clittelum.

Make sure not to cut too deeply!!

Continue your cut to the mouth

Begin to separate the skin using pins

Pin the skin back as you go along the cut. Angle your pins outward so that are out of the way.

As you pin the skin back, take your probe and break the partitions between the segments. These are called Septum.

Pharynx

Aortic Arches – Earthworms have 5 pair of these simple hearts.

Aortic Arch

Seminal Vesicles

Seminal Receptacles

Crop

Gizzard

Dorsal Blood Vessel

Intestine

Ventral Nerve Cord

Ventral Nerve Cord

Brain (Cerebral Ganglion)

Nerve Cord and Brain

Brain