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chestnut lamprey

chestnut lamprey (Ichthyomyzon castaneus) Photo © Uland Thomas

Features and Behaviors


The chestnut lamprey larva may grow to six inches or more in length. The larva does not have eyes, and its mouth is shaped like a horseshoe. The adult's mouth is as wide or wider than the head and contains sharp teeth. A cartilage skeleton supports the yellow or tan body. This fish has one dorsal fin.


The chestnut lamprey lives in lakes and streams. This fish reaches maturity at a length of 10 to 12 inches. The adults move into streams to spawn in late winter and spring. The female may deposit more than 42,000 eggs in a nest that is hollowed out on the stream bottom. 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. The larval stage lasts three to six years. The adult may live about 18 months, but it feeds for only about five months midway through its life span. The adult chestnut lamprey is parasitic on 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