Like an ocean-going vampire, the adult sea lamprey survives by sucking the blood of bigger fish. This lamprey has a mouth that works like a suction cup and attaches to victims so the creature can drink its dinner. Once it latches on to a host, the lamprey can rarely be shaken loose.
Clamp Down: Rows of small teeth inside the creature's disk-shaped mouth help it clamp onto prey. These teeth and a jagged-edged tongue scrape away a fish's scales and get the victim's blood flowing.
Biggie Size: The adult sea lamprey fills up on blood by preying on the largest fish it can find. Many victims don't survive, and the lucky ones that do make it have round scars left on their skin.
Great Lakes Invasion[]

The sea lamprey can attach itself to a rock or unsuspecting victim by using its mouth.
Sea lampreys swim into freshwater rivers to breed, and some have made incredibly long journeys. Through a system of rivers and canals, these parasites have invaded all five of the Great Lakes between the U.S. and Canada. Since then, fish populations in the lakes have decreased by millions and caused fisheries in the area to go out of business. The U.S. and Canadian governments have used chemicals and underwater electrified fences to stop the lampreys, but have had little luck.
In and Out: Unlike other fish, a lamprey's gills are made up of seven holes behind each of its eyes. This sea creature breathes taking in water through a small opening in its mouth, even while feeding. Oxygen is absorbed from the water and the rest passes out through the gills.
Low Life: Lamprey larvae don't have eyes and spend seven years mostly buried in the seabed, eating tiny organisms they find in the sand. Adults feed only on blood for the last two years of their lives.
The Bigger the Better[]
- On the lookout for a big meal, a sea lamprey spots a large sea trout. The lamprey sprints toward the fish by rapidly moving its single-finned tail.
- The lamprey grabs onto its victim's scales and scrapes them away with its teeth and rough tongue. Blood begins to flow when the teeth bite into the fish's soft flesh.
- The sea trout is powerless against the lamprey as its blood is sucked out. The lamprey drinks so much that the trout is too weak to swim after the parasite leaves.
Trading Card[]
Trivia[]
- This is one of the few purely saltwater fish not included in Monsters of the Deep, along with Barracudas, Stingrays, Mudskipper, Seahorses, Leafy Sea Dragon, Flying Fish, Clownfish, and Remora.
- Both photos on the back of the knowledge card are shared with the Wildlife Explorer series.