Massive congregation of aquatic leeches at an agricultural ditch-wetland. The majority of leeches live in freshwater environments, while some species can be found in terrestrial and marine environments, as well. Most leeches are hematophagous, as they are predominantly bloodsuckers that feed on blood from vertebrate and invertebrate animals. Almost 700 species of leeches are currently recognized, of which some 100 are marine, 90 terrestrial and the remainder freshwater.
Hypnotizing to Watch: Leeches Swimming
Video by Eamericanus777