lamprey

Imagine a creature that looks a bit like an eel, with a round mouth made for sticking to other fish. That's a lamprey. These ancient fish are known for their circular sucking mouths, lined with rows of teeth. Many species attach themselves to fish and feed on blood and body fluids. Some kinds do not feed as adults, but others are parasitic and can leave their host weak or badly hurt. Lampreys have been around for more than 500 million years, long before dinosaurs. You may hear about them as a serious invasive species in places like the Great Lakes, where they have harmed native fish populations.

Lampreys are an ancient lineage of jawless fish characterized by their eel-like bodies and unusual feeding habits. They belong to a group called cyclostomes, meaning "circle mouth," a reference to their round oral disc lined with sharp teeth for latching onto other animals. There are around 40 species of lamprey found in temperate regions around the world.

Some lampreys are anadromous, meaning they live most of their lives in saltwater but migrate into freshwater rivers and streams to spawn—much like salmon. However, unlike salmon, lampreys don't have jaws; instead, they use their sucker-like mouths to rasp away at the flesh of their host or simply suck blood.

There are two main types: parasitic lampreys and non-parasitic lampreys. Parasitic species attach themselves to other fish using their oral disc and teeth, feeding on their host's tissues and fluids. This can be devastating for local fish populations. Non-parasitic lampreys, by contrast, do not feed at all as adults; they live off energy stored from their larval stage, reproduce, and then die.

Lampreys have a fascinating (and sometimes unsettling) history. They were considered delicacies in medieval Europe and were famously favored by royalty. Today, however, they are often viewed as pests, particularly the sea lamprey, which has caused significant ecological damage in the Great Lakes. Control efforts focus on using barriers and specialized chemicals to prevent their upstream migration to spawning grounds.

Whether you're learning about ancient fish evolution or dealing with an invasive species problem, the lamprey is a remarkable—and sometimes frightening—creature that embodies millions of years of natural history.