Earthworm Dissection Photo Credit: All photos taken from http://www.flushing.k12.mi.us/srhigh/mignerey/web%20dissections/earthworm%20web/Frameset.htm Some content from: http://www.scienceclass.com/dissect/teacher_materials/glossary/earthworm_glossary.html Various videos from both www.YouTube.com and www.arkive.com
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 Dorsal blood vessel Aortic arches Ventral blood vessel Dorsal blood vessel Go To Nervous System
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
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
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
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.