FaunaHub

Lamprey (e.g. Petromyzon marinus)

FishJawlessLiving fossil

Sea lamprey (Petromyzon marinus) showing its round, toothed sucker mouth.

Sea lamprey (Petromyzon marinus).

Image: Photo Credit: Great Lakes Fishery Commission, Public domain, via Wikimedia Commons.

Overview

Lampreys are ancient, eel-shaped fish that belong to one of the oldest surviving lineages of vertebrates. They are jawless — instead of jaws, they have a round, funnel-like sucker mouth lined with rings of horny teeth and a rasping tongue. Lampreys have no scales, no paired fins, and a skeleton of cartilage rather than bone, and they are not closely related to true (bony) fish despite their similar shape. The sea lamprey (Petromyzon marinus) is shown here.

Many of the well-known lampreys are parasitic as adults, latching onto other fish with the sucker mouth to feed on blood and body fluids — though a number of lamprey species do not feed at all as adults.

Note: there are many lamprey species with different habits; details here use the sea lamprey as a reference. Treat general statements as approximate and verify against authoritative sources.

Habitat & Range

Lampreys live in temperate fresh and coastal waters of the Northern and Southern Hemispheres. Many are anadromous — adults live in the sea or large lakes and migrate up rivers to spawn — while some species spend their whole lives in fresh water. Their larvae burrow in the soft beds of rivers and streams, so clean, flowing fresh water is essential to their life cycle.

Diet

Parasitic adult lampreys feed by attaching to a host fish with their sucker mouth, rasping through the skin, and drinking blood and body fluids, often without killing the host immediately. Their long-lived larvae, by contrast, are harmless filter feeders, buried in river sediment and straining tiny food particles from the water. Some lamprey species do not feed at all in the brief adult stage and simply spawn and die.

Behavior

The lamprey life cycle is remarkable: eggs hatch into blind, toothless larvae (called ammocoetes) that spend years buried in river beds filter-feeding. They then transform into the familiar toothed adult, and parasitic species head out to feed on fish before returning to fresh water to spawn — after which the adults die. With their cartilage skeleton, sucker mouth, and jawless anatomy, lampreys preserve features of very early vertebrates, making them important “living fossils” for understanding the origins of backboned animals.

Human Interaction & Conservation

Lampreys have a long and varied relationship with people: some have been eaten as a delicacy for centuries, many native lampreys are of conservation concern as rivers are dammed and polluted, and yet sea lampreys became a notorious invasive pest in the North American Great Lakes, where they devastated fish populations and are now actively controlled. So lamprey status ranges from threatened to invasive depending on the species and place. Consult authoritative sources for specifics.

More photos of the lamprey

A lamprey, an eel-shaped jawless fish.

Sea lamprey (Petromyzon marinus).

Image: Matt Garvin, CC BY-SA 4.0, via Wikimedia Commons.

Frequently Asked Questions — Lamprey

What is a lamprey's mouth like?
Instead of jaws, a lamprey has a round, funnel-shaped sucker disc lined with concentric rings of horny teeth, plus a rasping tongue. Parasitic lampreys use this to clamp onto a host fish, file through the skin, and feed on blood and body fluids. The jawless sucker mouth is the lamprey's most distinctive feature.
Are lampreys fish?
They are often grouped with 'fish,' but lampreys are jawless vertebrates, quite different from the true (bony and cartilaginous) fish. They lack jaws, scales, and paired fins, and have a cartilage skeleton. Lampreys belong to an ancient lineage that branched off very early in vertebrate evolution, which is why they're studied as living relics of early backboned animals.
Do all lampreys suck blood?
No. Many familiar lampreys are parasitic as adults, feeding on the blood and fluids of other fish, but a substantial number of species are non-parasitic — their brief adult stage doesn't feed at all; they simply spawn and die. And all lampreys spend years as harmless, filter-feeding larvae buried in river beds.
Why are sea lampreys a problem in the Great Lakes?
Sea lampreys invaded the North American Great Lakes (helped by shipping canals) and, with no natural controls, attacked native fish in huge numbers, contributing to the collapse of important fisheries. They are now the target of an extensive, ongoing control program, even as native lampreys elsewhere are protected — a striking contrast in how the same group of animals is managed.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.