Observations on the physiology and phylogeny of colour change in marine and freshwater leeches (Annelida: Hirudinea)

A jumping terrestrial leech from Madagascar

“…Interestingly, we find that the jumping Chtonobdella leech does not appear to be a climbing specialist. Again, a variety of colorful leeches, such as H. picta (the so called “jumping leech” (Sawyer et al., 1982)), are often the species that live up higher in the understory and have been debated as to whether they jump. The leeches in the videos have dull colors, making them well‐camouflaged against forest floor leaf litter.…”

“…For instance, in reference to H. picta in Brunei, Sawyer stated: "It is erroneously called the jumping leech because, when disturbed, it may release its caudal sucker and fall (Sawyer et al, 1982)." Based on the anecdotes described above, it does seem like there is more willingness for scientists and others to give support to leeches' ability to drop off of vegetation and onto unsuspecting hosts, even if authors are less clear on how frequently this may occur.…”

“…To be explicit, most haemadipsid leeches have not been specifically thought to jump. It is only a small subset of species such as Haemadipsa picta— also called the “jumping leech”—that are typically under debate as to whether they can or cannot jump (Sawyer et al., 1982). In general, the leeches that have been suggested to jump live in bushes and shrubs.…”

“…Other authors have considered these possible issues of semantics. For instance, in reference to H. picta in Brunei, Sawyer stated: “It is erroneously called the jumping leech because, when disturbed, it may release its caudal sucker and fall (Sawyer et al., 1982). "…”

Taxonomy and Melanism Patterns of Freshwater Leeches in the Genus Glossiphonia (Hirudinea: Glossiphoniidae) from Northeast Asia

“…Considering these occasional observations, we could assume that light-colored and melanic forms in this species may reflect substrate-induced cryptic coloration, but this preliminary hypothesis needs to be statistically checked in the future. Conversely, Sawyer and Dierst-Davies [62] showed that individual leeches darken in the light and lighten in the dark and that they do not adapt to the background. From this perspective, a larger proportion of melanic individuals in the Arctic could be linked to the polar day (midnight sun) phenomenon, i.e., extended period of daytime occurring in areas north of the Arctic Circle during the summer months.…”