Hirudo verbana uses anticoagulants when it feeds, so its bite wounds continue bleeding for some time afterwards.

Within its crop, water and some osmolytes are removed from the consumed blood and excreted through a series of nephridia and bladders.

[5] Like other leeches, H. verbana has anterior and posterior suckers that allow it to attach to a range of substrates in both air and water.

In the wild, this ability may be relevant for attaching to porous rocks or the furry skin of host animals.

The intestinum has a more diverse microbiome, containing (in addition to Aeromonas and Rikenella-like bacteria) Firmicutes, Fusobacteria, Morganella morganii and members of the α, γ, and δ Proteobacteria.

These may benefit the leech by providing nutrients which are scarce in blood (e.g. B vitamins) or reducing colonisation of the gut by harmful bacteria.