Slimy, wriggling, and with three to four rows of skin-slicing teeth, leeches seem to have a bad reputation. Let’s take a look at these often misunderstood segmented worms. Here are some things to know about and some reasons to appreciate leeches!
Of the over 600 species of leeches spread from the tropics to the Antarctic waters, only about ten percent are parasitic – that’s only a couple North American freshwater species. Most leeches subsist on decaying matter and invertebrates. Leeches also serve as food for fish and birds, so they are an important part of watery food webs. For example, common grackles pick leeches from basking map turtles, and minnows pluck them from wood turtles.
If you do get a leech bite, you likely will not feel it. Their saliva contains a natural anesthetic, along with histamine-like secretions to dilate blood vessels and anticoagulants to increase blood flow.
While leeches have a rather iffy history of being used for bloodletting, today they are used by some medical practitioners to restore healthy blood flow after reconstructive surgery.
Next time you see a leech, perhaps crawling along like an inchworm using anterior and posterior suckers, take a moment to notice and wonder, and to appreciate what it takes to survive in nature.