Saskatchewan Leeches (Hirudinea)

Four families have been recorded from Saskatchewan totally at least twenty-seven species.

Leeches are easily recognised by their segmented "worm" appearance and the anterior and posterior suckers on the ventral surface. They are also recognized for their blood sucking ability but as with many organisms only a few "suck" mammalian blood. Unfortunately their striking colors usually do not with stand preservation and the body contracts to only a fraction of their full length so it is best to note their colour while they are alive. The fully extended size can range from 10 mm for the small species to over 100 mm for the horse leech, Percymoorensis marmorata (Say).

Below is a basic taxonomic key to the families of leeches found in SK.

I find the eyes are useful for identification when the leech has been preserved in alcohol and much of the color is lost and the body is contracted.

1a: Mouth situated in a large disc like front sucker . Back sucker also enlarged relative to body.--Piscicolidae (Fish Leeches)

1b: Front sucker not disclike and appears continuous with the body.--Go to 2

2a: Mouth a tiny opening in the front rim of the anterior sucker. One pair of eyes or a row of three or four pairs of eyes.--Glossiphoniidae

2b: Mouth a large opening. 3

3a: Five pairs of eyes present along the periphery of the first segments. Large leeches, mature specimens usually greater than 100 mm when relaxed.--Hirudinidae

3b: Three pairs or four pairs of eyes. Length from 60 to 100 mm.--Erpobdellidae

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References:

Clifford, H.F. 1991. Aquatic Invertebrates of Alberta. University of Alberta Press. Edmonton, Alberta.

Davies, R.W. 1991. In Thorp, J.H. and A.P. Covich. Ed. Ecology and Classification of North American Freshwater Invertebrates.

Davies, R.W. 1973. The geographic distribution of freshwater Hirudinoidea in Canada. Can. J. Zool. 51:531-545.

Oliver, D.R. 1958. The leeches (Hirudinea) of Saskatchewan. Can. Field-Nat. 72:161-165.