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silver lamprey

​silver lamprey (Ichthyomyzon unicuspis)
Photo © Konrad P. Schmidt, University of Minnesota

Features and Behaviors


The silver lamprey has a shallow notch in the dorsal fin. When held open, its mouth disc is wider than its head. Larvae and immatures are yellow in color while adults are blue to black. Larvae may reach seven inches in length while full grown adults may be about 15 inches long.


The silver lamprey may be found in the Mississippi, Illinois, Kaskaskia, Ohio and Wabash rivers in Illinois. This fish lives in large rivers and lakes and spawns in spring in medium-sized streams with sand and gravel riffles. The ammocoete is the blind, larval form that hatches from the egg. It burrows into the stream bottom with its head sticking out to filter microscopic organisms that pass by. Larval development of the silver lamprey takes four to seven years. The adult form lives for about one year. The adult is an external parasite of fishes. It attaches to a fish and scrapes a hole in the body through which it may suck out blood and tissue fluids. After feeding on a fish in this manner for several days, the lamprey drops off. The fish is generally not killed directly by the attack but may die due to infections that invade through the wound.

Illinois Range


​Kingdom: Animalia
Phylum: Chordata
Class: Cephalaspidomorphi
Order: Petromyzontiformes
Family: Petromyzontidae

Illinois Status: common, native