Aquatic worm is a term used to describe a variety of worms that live in water. The most common type of aquatic worm is the LEECH, which has five letters. Leeches are segmented worms that feed on the blood of other animals and can be found in both fresh and salt water. BAIT, which has four letters, is often used to attract aquatic worms. INCH, also with four letters, is a unit of measurement used to describe the size of aquatic worms.