Leeches are fascinating creatures, belonging to the segmented worm phylum Annelida, much like earthworms. These soft-bodied invertebrates are known for their ability to expand and contract, making it challenging to determine their exact length. While some species are well-known for their blood-feeding habits, many others are predatory or scavengers, playing an ecological role in their environments.
Leeches Present in Missouri
Leeches are found throughout Missouri, inhabiting various freshwater environments across the state. Missouri’s leeches vary in size, from half an inch to over 20 inches. They often appear in shades of black or brown, though some species exhibit bright colors or attractive speckled and striped patterns.
Many Missouri leech species are predatory, consuming smaller aquatic animals whole, while others are parasitic. Parasitic leeches attach to hosts like fish, amphibians, reptiles, or mammals, including humans. When a parasitic leech attaches, it secretes an anesthetic to numb the area, making the bite often initially painless, and an anticoagulant to prevent blood from clotting.
Typical Habitats
Leeches in Missouri are most commonly found in warm, calm, and shallow freshwater bodies. They prefer habitats like ponds, lakes, slow-moving rivers, streams, and marshes. They thrive in areas rich with vegetation and debris, providing shelter and foraging opportunities.
Leeches generally avoid direct light, seeking refuge under stones, submerged logs, or within the bottom muck. While they can “loop” among plants in gently moving waters, they are less prevalent in fast-flowing, clear rivers. Their adaptability allows some species to burrow into mud during dry conditions, surviving for extended periods until water returns.
What to Do About Leeches
Most leeches in Missouri are not considered dangerous to humans. They rarely transmit diseases, and any discomfort from a bite is typically minor, often limited to itching or minor bruising. The initial bite is usually painless due to the anesthetic properties in the leech’s saliva, though minor bleeding can occur after detachment because of the anticoagulant.
To avoid leeches, wear protective clothing like long pants and closed-toe shoes when entering their habitats, especially in stagnant or shallow, vegetated waters. After leaving the water, check your body and clothing for any attached leeches. If a leech does attach, gentle and safe removal is recommended.
To remove a leech, locate its head and mouth, typically the narrower end, then gently slide a fingernail or a thin, blunt object like a credit card underneath to break the suction. Flick the leech away to prevent reattachment. Avoid harsh methods such as salting, burning, or forcefully pulling the leech, as these can cause it to regurgitate stomach contents into the wound, potentially increasing the risk of infection. After removal, clean the bite wound with soap and water, apply an antiseptic, and cover it with a sterile bandage. The wound may continue to bleed slightly due to the anticoagulant, but it typically heals on its own within a few days.