Earthworms Galore
by: Hannah Katz teacher: Ms. Vu
The Earthworm
This picture shows a cross section in an earthworm. Here is a list of the parts of the cross section:
-dorsal blood vessel
-typhlosole
-peritoneum
-setae
-nephridium
-nephrostome
-nephridiopore
-ventral blood vessel
-lateral-neural blood vessel
-subneural blood vessel
-chloragogen cells
-submucosa
-mucous membrane
-cuticle
-epidermis
-intestine
-coelom
-nerve cord
-circular muscle layer
-logitudinal muscle layer
Digestive System
The digestive tract of the earthworm is a straight tube which extends from the worm's mouth to its anus. It is differentiated into a pharynx, gizzard, crop, buccal cavity, intestine, and esophagus. Food enters through the mouth and is brought to the pharynx. The pharynx's muscular walls draw in food. In the pharynx, the pharyngeal glands secrete mucus. Food moves into the esophagus, where calcium is pumped in to maintain proper blood levels. From there the food passes into the crop and gizzard. In the gizzard, strong muscular contractions grind the food with the help of mineral particles ingested along with the food. Once through the gizzard, food continues through the intestine for digestion. The intestine secretes pepsin to digest proteins, cellulase to digest cellulose, lipase to digest fat, and amylase to digest polysaccharides. Instead of being coiled like a mammal's intestine, an earthworm's intestine is long and thin and has many folds running along its length.