Regeneration

• The vital organs needed for regeneration are found in the front half of the worm. If it is cut in half, this portion can grow a new tail that will be smaller in diameter and sometimes lighter in color than the original. The tail end can not grow a new head and will eventually die, although it will continue wriggling until its stored food resources run out.
  
  

Clitellum

• The earthworm's reproductive organs are contained in the clitellum, a thickened glandular section about a third of the way down its body. If the earthworm is to survive and grow a new tail, it must be severed below the clitellum.
  
  

Function

• Earthworms have developed the ability to survive being cut in two to help fend off attacks from such predators as birds. The ability to regenerate varies by species. It also depends on how much damage was caused.
  
  

HIstory

• There were no earthworms in North America until European settlers arrived in the 17th and 18th centuries.