They are also sometimes called 'bootlace worms'. Examine the demonstration specimen of Emplectonema and you will see why. They are mainly marine forms and some can be highly coloured. A few species are found in moist soil and freshwater habitats but the majority are marine. Although very similar to Platyhelminthes there are some important differences - the digestive tract is complete, with an anus, allowing the excretion of waste.
Nemerteans are also more advanced in having a circulatory system.