What lampreys eat?

- Plankton-filtering lampreys: Some species of lampreys, such as the Pacific lamprey (Entosphenus tridentatus), are plankton-filtering feeders as adults. They use their specialized mouthparts to filter small planktonic organisms, including algae, zooplankton, and other microscopic animals, from the water.

- Parasitic lampreys: Other lampreys, such as the sea lamprey (Petromyzon marinus) and the American brook lamprey (Lampetra appendix), are parasitic feeders during their adult stage. They attach themselves to the bodies of fish hosts, using their specialized rasping tongue and teeth, and feed on the host's bodily fluids and tissues. Parasitic lampreys can cause significant damage to host fish, leading to injury, weakened immune systems, and even death in some cases.

During their larval stage, known as ammocoetes, most lamprey species are filter feeders. They inhabit substrates like sand or mud, where they use their mouthparts to collect organic matter, diatoms, and other small organisms from the water.