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Earthworm Digestion
Earthworms have an outer tube -- the surface we see -- and an inner tube, which is the worm's digestive system. Like a human, a worm consumes food through one end and excretes waste through the other, extracting the nutrients it needs as the food passes through the alimentary canal. A worm's alimentary canal, like a human's, has several parts. Specialized sensory cells in the "mouth," called the buccal cavity, detect chemicals the worm needs such as sucrose and saline. The worm has a pharynx, esophagus, crop, gizzard, intestine and anus, each of which plays a role in its digestive and excretory process. Like humans, worms benefit from that live in their alimentary canals and aid in digestion.
Earthworm Circulation
Earthworms have five "hearts" with valves and chambers. Though simpler than a human's heart, these organs perform the same basic function of keeping the worm's blood flowing as it distributes oxygen and nutrients throughout the body. Humans have arteries to carry freshly enriched blood away from the heart, and veins that return the depleted blood to be refreshed; earthworms have ventral and dorsal vessels that perform the same basic functions. Like a human's, an earthworm's blood is red.
The Earthworm's Nervous System
An earthworm has a structure called the cerebral ganglion located near its front end that processes sensory information vital to the worm's survival such as moisture, light and temperature, and controls the worm's responses to these stimuli. Biologists believe that the central ganglion also regulates reproduction and other vital functions.
Earthworm Reproduction
Every earthworm has both male and female reproductive organs and can produce both eggs and sperm. Despite this versatility, worms cannot reproduce alone. Like a human, a worm needs to mate with another worm to create offspring.