Lampreys are ancient, jawless aquatic vertebrates recognized for their unsettling, circular, toothed mouths. These eel-like creatures have maintained their unique form for over 340 million years. Their appearance and parasitic habits raise public concern regarding potential interactions with humans. This article examines the lamprey’s feeding mechanism, the risk of human encounters, and the consequences of accidental attachment.
Lamprey Biology and Feeding Mechanism
Lampreys belong to the infraphylum Agnatha, classifying them as jawless fish. Most species begin life as blind, toothless, filter-feeding larvae called ammocoetes, which can remain burrowed in freshwater sediment for years. Upon metamorphosis, parasitic species develop the characteristic oral disc necessary for adult feeding.
The adult mouth is a large, funnel-like structure that functions as a suction cup, surrounded by rows of sharp, keratinized teeth. These teeth help the lamprey maintain a secure grip on its host fish. Inside the oral disc is a piston-like tongue tipped with horny plates, which the lamprey uses to rasp through the host’s scales and skin.
Once a wound is created, the lamprey secretes a substance from its buccal glands containing powerful enzymes, including an anticoagulant called lamphredin. This secretion prevents the host’s blood from clotting, allowing the lamprey to feed on blood and body fluids. The parasitic phase can be highly destructive; a single sea lamprey is capable of destroying up to 40 pounds of fish during its adult life.
Human Encounters: Likelihood and Context
Lampreys do not intentionally target warm-blooded mammals like humans; their parasitic feeding strategy is adapted specifically for cold-blooded fish. Documented instances of human contact are extremely rare and accidental, usually occurring when the lamprey mistakes a large, submerged object for a host. Swimmers in freshwater bodies, particularly the Great Lakes where the invasive Sea Lamprey is prevalent, are the most likely to experience accidental attachment.
The risk varies significantly depending on the species and location. Non-parasitic species, such as the American brook lamprey, do not feed after their larval stage, posing no threat. Parasitic species, like the Sea Lamprey, are typically found in the Atlantic Ocean and Great Lakes, where they are a major concern for fisheries.
Accidental attachment may also occur when anglers or researchers handle captured specimens. In these rare situations, the lamprey is likely reacting defensively or attempting to latch onto a surface. The attachment is often brief, as the lamprey usually detaches quickly once it recognizes the difference between human skin and a cold-blooded fish host.
Immediate Effects of Attachment and Treatment
If a lamprey attaches, the resulting injury is typically a superficial circular abrasion or suction mark, not a deep wound. The teeth are designed for grip and rasping fish scales, not for puncturing thick human skin. While the initial attachment can be painful, the lamprey will not consume human blood or tissue for an extended period.
The immediate consequence of attachment is minor bleeding due to the anticoagulant enzymes secreted by the buccal glands. The most significant medical concern is the potential for a bacterial infection at the site of the skin break. Like any open wound sustained in natural water, it is susceptible to waterborne pathogens.
The correct procedure for removal is to gently break the suction seal rather than pulling the lamprey off forcefully, which could tear the skin. Once detached, the wound should be cleaned thoroughly with soap and water to minimize the risk of infection. Applying an antiseptic and covering the area with a sterile dressing is recommended. Medical attention should be sought if the wound shows signs of deep infection, such as increasing redness, swelling, or pus, or if the individual experiences fever or an allergic reaction.