Tiger worms, also known as red wriggler worms, or simply redworms, are a type of composting worm. These worms, typically identified by the scientific name Eisenia fetida, are generally reddish-brown in color and often seem to have stripes, because their bodies are segmented. Tiger worms typically have no eyes or ears, but are usually able to detect heat, light, and movement in the soil around them. These worms do not have any teeth, but use a combination of digestive enzymes and small particles of debris within their bodies to break down and digest their food. Tiger worms can take in both water and air directly through their skin, and they are generally hermaphroditic, so that they can mate and reproduce without the benefit of a partner.
The species of worm commonly known as the tiger worm usually lives on the soil's surface, or no deeper below the surface than about 10 inches (25.4 centimeters). Tiger worms typically thrive best at temperatures between 68 and 77° Fahrenheit (20 to 25° Celsius). They usually can't survive temperatures higher than 90° Fahrenheit (32.2 Celsius). Tiger worms usually need plenty of moisture in their soil environment, and are said to prefer soil that contains 43 to 90 percent water. The ideal soil pH for this species of worm is believed to range from five to nine on the Blakemore pH scale.
These worms reproduce by depositing both sperm and eggs into a cocoon. Their bodies secrete a sticky substance that hardens to form this cocoon. Tiger worms are generally hermaphroditic, meaning that each individual possesses the ability to create both sperm and eggs. As a result, they are normally able to fertilize their own eggs themselves, without need of a sexual partner. The eggs generally take about two months to hatch, and the young worms will reach sexual maturity in an average of two months to ten weeks.
This species of composting worm is often bred and sold to gardeners. Worm farmers usually sell tiger worms in 2.2-pound (1-kilo) increments. These worms are believed capable of laying eggs every two weeks for up to a year, and each cocoon is believed capable of hatching up to 20 new worms. Worm farmers usually estimate that these worms will reproduce quickly in a well-suited garden environment, and they are often capable of doubling their population in about 60 to 90 days.