Leech

Found in both freshwater and marine environments, as well as some moist terrestrial habitats like rainforests.

Some species are hematophagous (blood-feeders) on vertebrates or invertebrates, while others are predators of small invertebrates like worms and snails.

They move via an 'inchworm'-like looping motion and are known for their ability to attach themselves to hosts via suckers. Many are nocturnal or hide under debris.

Risks include skin irritation and potential infection from bites; benefits include medicinal use (hirudotherapy) to improve blood flow after surgery and their role as indicators of water quality.