Haementeria ghilianii

Haementeria ghilianii, the giant Amazon leech, is one of the world's largest species of leeches.^[1] It can grow to 450 mm (17.7 in) in length and 100 mm (3.9 in) in width. As adults, these leeches are a greyish-brown colour, as opposed to juveniles, which do not have a uniform colour, but rather, a noncontinuous stripe of colour, and patched colouring. They live from the Guianas to the Amazon.^[2] The leech produces the anticoagulant protease hementin from its salivary glands.

Sources

1. ↑ http://invertebrates.si.edu/Features/stories/haementeria.html
2. ↑ http://animals.jrank.org/pages/1697/Leeches-Hirudinea-GIANT-AMAZONIAN-LEECH-Haementeria-ghilianii-SPECIES-ACCOUNTS.html