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Annelids : Earthworms 
Earthworms (also called nightcrawlers) are very important animals that aerate the soil with their burrowing action and enrich the soil with their waste products (called castings). Good soil can have as many as as 1,000,000 (a million) worms per acre.
There are over 3,000 species of earthworms around the world. These invertebrates (animals without a backbone) range in color from brown to to red, and most have a soft body. Earthworms range in size from a few inches long to over 22 feet long. The largest earthworms live in South Africa and Australia. Anatomy and DietThe brain, hearts, and breathing organs are located in the first few segments of the worm. It has five pairs of hearts! The rest of the inside of an earthworm is filled with the intestines, which digest its food. Earthworms eat soil and the organic material in it - like insect parts and bacteria. The mouth is covered by a flap (called the prostomium) which helps the earthworm sense light and vibrations. Tiny bristles (called setae) are on most segments of the earthworm's body. ReproductionAlthough each earthworm is hermaphroditic (having both male and female reproductive systems), it takes two worms to mate and reproduce. The reproductive organs are in the clitellum (the enlarged segments in the middle of an earthworm). The clitellum later forms a cocoon which protects the developing eggs. |
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