How Well Can Earthworms Regenerate?

Types of Earthworms

• There are as many as 2,700 species of earthworms, according to the University of Illinois Extension Service. The ability to regenerate varies from one earthworm species to another, but most species are at least able to regenerate new tails if the tail is cut off. Different species can regenerate beyond different segments of the body. Most require at least half of the body to be undamaged in order to regenerate. Some can only regenerate one or two segments at the tail end of the body. Although earthworms can regenerate parts of their bodies, certain other types of worms can survive decapitation and will regenerate two worms if cut in half, according to Northwestern University.

Earthworm Parts

• Earthworm regeneration is possible because of the structure and simplicity of the body. They have no skeleton or eyes, but they have well-developed muscular, circulatory, nervous, digestive and reproductive systems. The outside of an earthworm is characterized by segments which involve almost all the internal structure. Red worms and manure worms have about 95 segments, while nightcrawlers have about 150 segments, according to the University of Florida IFAS Extension. Different segments perform different functions.

Amount of Damage

• The amount of damage is definitely a factor in an earthworm's ability to regenerate. While some species of earthworms can't regenerate more than one or two segments at the tail end, others can regenerate almost half the body as long as the head and clitellum are intact. The clitellum is the bump in the middle of an earthworm. It has reproductive functions, and it secretes mucus and holds embryos. The eventual disappearance of this body part signals old age.

Considerations

• Regeneration of earthworms is a defense mechanism that helps earthworms to survive. If a bird snips off the worm's tail, the worm simply grows a new one. The part that is clipped off will die, while the head and front portion of the worm will survive and regenerate. Moist soil conditions are required for an earthworm to survive or regenerate. Earthworms can survive in conditions of 50 to 70 degrees Fahrenheit. If the weather is cold or dry, earthworms are not active. If an earthworm is exposed to sunlight for a period of time, it becomes paralyzed and will die if it is not returned to a moist environment.