How big is the largest leech?

Reaching nearly 18 inches long and four inches wide, the Amazon leech is the world's largest. The dark gray-brown species is found from the mouth of the Amazon and north to Venezuela and the Guianas on the continent of South America.

Known to live for up to 20 years, the giant Amazon leech lives in wetland marshes and is often located under rocks and other debris. Young bloodsuckers usually attack amphibians, while adults feed on anacondas, caimans, capybaras and domestic cattle. A special chemical found in the saliva of the leech has been used to break down blood clots in humans.