Traits

Similar to Siren, wyvern-bodied leeches have developed only their hind legs. So far this has only been recorded in cave leeches, where there is less emphasis on the aquatic lifestyle of their aboveground cousins.

Many leeches with this trait are seen with wings which they use as rudimentary forelegs, resulting in an odd hopping or wiggling gait (completely different to leeches who have wings attached as a side-trait to their existing forelegs!), while those without wings have larger tails to act as a counterweight and could be better compared to dinosaurs.
These leeches have a very aggressive prey drive, and will bite first and ask questions later, striking hard and fast to both kill and swallow their food as without forelegs they do not have the mobility to hunt by other means.