Earthworm Dissection Photo Credit: All photos taken from Some content from: Various videos from both and

External Anatomy

Cuticle – keeps the worm from drying out

Dorsal – top part

Ventral – bottom part

Clitellum- makes mucus that dries up to form a cocoon

Prostomium – covers the mouth of the worm

Mouth- opening at the end allowing the intake of food consisting of particles of both living and dead substances

Setae – bristle like structures that help the worm move

Sperm Duct – openings in which sperm can pass through

Sperm groove – sperm moves along here from sperm duct to another worm

Oviduct- tube through which eggs pass

Anus – where excrement (poop) comes out

Internal Anatomy

Circulatory System Aortic arches Ventral blood vessel Dorsal blood vessel Go To Nervous System

Aortic Arches - surround the esophagus and function in pumping the blood throughout the body

Ventral Blood Vessel- carries blood from the aortic arches to the rest of the body

Dorsal Blood Vessel- Returns blood to the aortic arches and has valves to prevent backflow

Nervous System Ganglion- group of nerves. In the earthworm, there is a pair of ganglia in each segment and a cerebral ganglia acts like a brain

Ventral Nerve Cord- connects the ganglia in each segment of its body with the cerebral ganglia. It coordinates movement

Excretory System Nephridium- filters wastes. Almost each segment of the worm has a pair of nephridia.

Digestive System Food goes from the: Mouth Pharynx Esophagus Crop Gizzard Intestine Anus

Pharynx- moves food from the mouth to the esophagus

Esophagus- Carries food between the pharynx and the crop

Crop – Stores food

Gizzard – grinds food

Intestine – Digests food

Mouth- opening at the end allowing the intake of food consisting of particles of both living and dead substances

Anus – where excrement (poop) comes out

Reproductive System

Seminal vesicles- store sperm produced by the earthworm

Seminal receptacles- paired organs that store sperm received from another worm during copulation

How do Earthworms Mate? Earthworms are hermaphrodites which means they have both mail and female body parts

Worms line up head to tail

Slime coats the clitellum

both of the earthworms begin to wriggle out of the slime tube

As they do this the tube passes over the sperm ducts and picks up sperm

Down the sperm groove

And mixes with eggs that come out of the oviduct

When free of the slime tube, the cocoon closes up and the sperm and eggs mix. This sac is carried by a worm until baby worms have developed, at which point the sac breaks open and they squirm free.