I've finally, after all these years, written an article on the animals my website is named after: [link]
Here we have the three most common categories of leech:
-"Proboscis" leeches feed through a telescopic, tongue-like tube and may be bloodsuckers, predators or scavengers.
-"Pharyngeal" leeches have toothless, expandable mouths and swallow earthworms whole.
"Jawed" leeches have up to three opposing, tooth-lined, wheel-like jaws and may also be carnivores, scavengers or parasites, including the "medicinal" leech.
All forms of leech may have from zero to eighteen eyes!
Again, read the article for more, and leave a comment on it if you can! [link]