I'll try to keep away from too much Latin usage and make this fairly brief. There are worms which live only in salt water, and worms which live only in fresh water. Some kinds live only in the ground, while others live exclusively above ground. There are worms which live only inside other animals, and worms which do not need oxygen to survive. Some worms are too small to see with the naked eye, while other varieties grow to 20 ft or more! The list goes on and on and on...

Every kind of worm has it's own lifestile, shape, coloration, manner of reproduction, strengths and weaknesses. Each kind has it's own niche in the ecology of the planet's food chain. As a group, worms amount to little more than eating machines, a mouth, digestive tract, excritory orifice, and are, at least to some degree, mobile. They are all simple creatures, little changed since the first ones appeared on the planet.

Pegging down the total number of varieties of worms has proven, for me at least, to be much like nailing jello to the wall... But if ya gotta have a number... more than 6,000 and, as researchers continue to look for and find new ones, that number can only increase.

Known or 'suspected' earthworm varieties exceed 3,000 ... or so say some of the experts.