Monday, June 29, 2020

Larry the Leech

Our great niece Taylor's friend, Luke found this leech in a puddle near the swimming hole.  Taylor said she recognized it from last year when it had a close relationship with her toe, then they named it Larry.  We explained that once you name an animal it achieves pet status and can't be killed or used for bait. I identified it as a Placobdella sp.  We renamed it "Della" and after the swimmers left it went back into the creek.

Ventral surface with stripes

Posterior sucker
The best match I found on INaturalist was a smooth turtle leech, Placobdella parasitica.  Wikipedia states that "P. parasitica is differentiated from other members of the genus Placobdella by its smooth dorsal surface, simple to complicated pigmentation, and abdomen with 8 to 12 stripes."  Positive identification requires dissection which Taylor was more than willing to do as payback.  Since some leeches can live up to 10 years she was certain this one had sucked her blood several times in the past.

Leeches are parasitic or predatory worms, distant relatives of our earth worms.  Most leeches are blood sucking parasites without a specific host species. They inject their saliva which contains anesthetic and anticoagulant chemicals, making their bite with serrated jaws painless.  Once they have had their blood meal they drop off and may not feed again for many months.

The MDC Field Guide is a good resource to start with.  A leech has a sucker on each end of its underside and can use them to move like an inch worm, stretching and expanding dramatically.  The head with the mouth is actually located at the small tapered end.  The power of its sucker can be seen here when I picked it up by the head end and it was able to lift a rock with its tail sucker!

Leeches have a long medical history dating back 3,500 years.  Even the word “leech” is derived from the English word “laece,” meaning physician. (Ouch!)  They were used for bleeding as treatment for a wide variety of diseases, and are still used in digital transplant and skin flap surgery to treat venous congestion.  Sciencedirect

Removing a leech should be done gently, trying to peel it off with a fingernail to avoid leaving mouth parts in the skin.  Salt, alcohol, turpentine or vinegar will cause it to detach but makes it vomit in the wound. (TMI)

Finally, some people are keeping leeches as pets.  Even though they are easy to raise and you only have to feed them every 3-6 months, Barb said "NO!"