InstructionsSea lamprey are not like other fish in the Great Lakes. They are part of a very old family of jawless fish that existed before dinosaurs! Sea lamprey are like sharks or your ears. Their bodies are made from cartilage and not bone. Sea lamprey made their way into the Great Lakes through man-made rivers. Now they harm other fish by sucking their blood. 
Sea lamprey lay eggs upstream from lakes in early Spring. They can move rocks as big as baseballs to create nests. A female sea lamprey can lay between 80,000 and 100,000 eggs in a season! How many eggs can a female sea lamprey produce?Not quiteTry again!See picture 1 to learn about sea lamprey eggs. Not quiteTry again!See picture 1 to learn about sea lamprey eggs. Correct!Sea lamprey only reproduce once in their lifetime. They produce a large amount of eggs all at once. After sea lamprey build their nests with rocks upstream and lay their eggs, they die.Not quiteTry again!See picture 1 to learn about sea lamprey eggs. 
After the eggs hatch, the young sea lamprey, called larva, do not feed on fish. They don't even have eyes or teeth! They will stay in the stream beds where they were born for 3 to 10 years. They filter food from the water. Before they move out to the lake they grow eyes, teeth, and a round mouth. How long do sea lamprey stay in the filter feeding stage?Not quiteTry again!See picture 2 to learn about the larval stage of sea lamprey. Not quiteTry again!See picture 2 to learn about the larval stage of sea lamprey. Not quiteTry again!See picture 2 to learn about the larval stage of sea lamprey. Correct!Sea lamprey stay in the streams for 3 to 10 years filtering food from the water with their gills. During this time they don't eat fish. Later they will develop eyes, a round mouth, and teeth and switch to eating fish.
Sea lamprey gill holes form a line behind the eye. Their gills are one of the things that allows them to move from the salty ocean to the freshwater Great Lakes. 
In the Great Lakes adult sea lamprey grow 1 to 2 feet long. Their mouths have 5 to 7 rows of teeth. They also have a sharp tongue to puncture their host's body. How many rows of teeth do sea lamprey have?Not quiteTry again!See picture 4 to learn about sea lamprey teeth. Correct!A sea lamprey's mouth allows it to attach onto their host fish. The teeth help keep hold of the fish. Their tongue acts like a knife to poke a hole in the skin of the host fish.Not quiteTry again!See picture 4 to learn about sea lamprey teeth. Not quiteTry again!See picture 4 to learn about sea lamprey teeth. How big do sea lamprey get in the Great Lakes?Not quiteTry again!See picture 4 to learn about how big sea lamprey get. Correct!Sea lamprey can reach up to 4 feet long in the ocean! Sea lamprey in the Great Lakes only reach 1 to 2 feet long. Why? Because the host fish in the ocean are larger than the ones in the Great Lakes.Not quiteTry again!See picture 4 to learn about how big sea lamprey get. Not quiteTry again!See picture 4 to learn about how big sea lamprey get. 
They have been a big problem for native fish like lake trout in the Great Lakes. An adult sea lamprey could have eaten 40 pounds of fish in their life. They are not harmful to humans. They can attach with suction, but they do not bite. Scientists use poison, barriers and other methods to remove sea lamprey from the Great Lakes and protect fish. How many pounds of fish do sea lamprey consume in their lifetime?Not quiteTry again!See picture 5 to learn about the sea lamprey's life as a parasite. Not quiteTry again!See picture 5 to learn about the sea lamprey's life as a parasite. Correct!A sea lamprey eats up to 40 pounds of fish in 12 to 18 months before it swims upstream to spawn.Not quiteTry again!See picture 5 to learn about the sea lamprey's life as a parasite. |
Last updated: January 6, 2026