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Mystery Photo I.D. – Leeches feeding on the blood of a Snapping Turtle

IMG_1812Leeches are segmented worms (annnelids) which feed predominantly on blood, although some species do eat insects. Of the 700 species of leeches, 500 inhabit fresh water, as opposed to salt water or land. Blood-sucking leeches are common parasites of many freshwater vertebrates including turtles, amphibians and fish.

Generally speaking, leeches of the genus Placobdella are commonly found on turtles. Bottom-dwelling species such as the Common Snapping Turtle, Mud Turtle and Musk Turtle usually have more leeches than other turtles, and they are often attached to the skin at the limb sockets. Aerially-basking species such as Painted Turtles often have fewer of these parasites, possibly because basking forces leeches to detach in order to avoid desiccation.

A leech can ingest several times its weight in blood from one host before dropping off and not feeding again for weeks, or even months. Leeches inject hirudin, an anesthetic, to keep the hosts from feeling them break the skin. They also inject an anticoagulant to keep the blood from clotting so that they can feed. Although leeches (especially large ones) can be a significant health detriment to smaller animals, they are not harmful to most large animals, such as Snapping Turtles.

Some of the most common predators of leeches include turtles, fish, ducks, and other birds. Map Turtles allow Common Grackles to land in basking areas and peck at leeches clinging to their skin, and minnows have been seen cleaning leeches from Wood Turtles in the water. At times turtles bury themselves in ant mounds to rid themselves of these pesky parasites.

For those readers who may hesitate before going into a leech-laden pond, it may be comforting to know that leeches are mainly nocturnal. (Photo by Jeannie Killam)

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8 responses

  1. Alice Pratt

    That was an amesome post, Mary! So much information. Thank you! My daughter and I were so intrigued by yesterday’s photo.

    July 7, 2017 at 7:14 am

  2. Clyde

    Leeches are nocturnal except for the political kind. They feed anywhere they can!

    July 7, 2017 at 7:41 am

  3. April

    MAINLY nocturnal, but not entirely. Please pass the salt.

    July 7, 2017 at 8:52 am

  4. Ruth Sylvester

    Hi Mary–
    Great slime and gore post!
    I think the graf about hirudin got crossed up, however. I think (and highly superficial google backs up) that hirudin is the anticoagulant. I don’ t know name of whatever anesthetic they use.

    July 7, 2017 at 9:41 am

    • Thanks so much, Ruth! I stand corrected not only with the hirudin, but the fact that they even have an anesthetic!

      July 7, 2017 at 10:36 am

  5. Kathryn


    July 7, 2017 at 9:58 am

  6. Kathie Fiveash

    Ugh. Can’t help it, sometimes nature is a bit disgusting.

    July 7, 2017 at 1:33 pm

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