This means that the earthworm releases nitrogen waste in the form of urea. Gas exchange in earthworms takes place at the moist skin of the animal. Blood carries carbon dioxide produced in aerobic respiration in cells to capillaries in the epidermis. There carbon dioxide diffuses from the blood into air spaces within the soil. This air space contains oxygen.
Oxygen diffuses into blood within the capillaries at the moist skin of the earthworm.
The most distinctive feature of annelids is segmentation. The Phylum Annelida includes three classes. Most oligochaetes live in soil, but a few like the tubifex worm that was on demonstration in lab live in fresh water. Some earthworm species found in Australia and Ecuador are seven feet long and an inch in diameter. These worms have distinct heads with eyes and tenacales, many bristles, and parapodia.