But unlike other worms they have a sucker at each end - one for feeding, the other for hanging on while they feed. Not all worms are Annelids. Some belong to a group called Nematodes .
Leeches are external parasites.
Habitat European leeches live in fresh water and damp places. There are a few marine leeches living in the Atlantic Ocean which prey on fishes. Now there are only a few ponds where this leech occurs naturally. And ponds are disappearing fast. On the whole leeches do not have bristles, but their flattened body allows them to swim effectively in an undulating way.