Lampreys: Cephalaspidomorphi

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LAMPREYS: Cephalaspidomorphi

SEA LAMPREY (Petromyzon marinus): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

Lampreys (LAM-prees) are scaleless, eel-like fishes that have skeletons of cartilage (KAR-teh-lej) instead of bone. Lampreys do not have jaws, so they cannot close their mouths. The mouth and tongue are covered with many small, sharp teeth. Adult lampreys are 8–47 inches (20–120 centimeters) long. Lamprey larvae (LAR-vee) look like worms. Larvae are the early form of an animal that must go through metamorphosis (meh-tuh-MOR-pho-sus), or a change in form, before becoming an adult.

GEOGRAPHIC RANGE

Lampreys live in coastal waters on both sides of the North Atlantic Ocean; the western part of the Mediterranean Sea; the western, southern, and eastern coasts of Australia; New Zealand; Tasmania; both coasts of South America; and the Great Lakes of North America.

HABITAT

Lamprey larvae bury themselves in the sand or mud of rivers. In the early phase of their lives, lampreys live in open water in oceans or lakes. They return to freshwater streams to spawn, or produce and release eggs.

DIET

Lamprey larvae feed on plankton, or microscopic plants and animals drifting in bodies of water, and algae (AL-jee), tiny plantlike growths that live in water. Lampreys attach themselves to other fishes and suck out their blood and muscle. Lampreys do not feed during the spawning phase of their lives.

BEHAVIOR AND REPRODUCTION

After three to seven years in a freshwater stream, lamprey larvae metamorphose (meh-tuh-MOR-phoz), becoming freely swimming and leaving the stream for the open water of a sea or lake. For one to two years, lampreys live as parasites (PAIR-uh-sites), which are animals or plants that live on other animals or plants without helping them and often harming them. They then return to freshwater streams to spawn, which they do only once and then die.

LAMPREYS AND PEOPLE

In some areas governments are trying to maintain or increase lamprey populations, because lampreys, which are food for other fishes and for birds, help fishermen. In some regions, however, lampreys are a problem, because during the parasitic phase they harm other fishes.

GREAT LAKES INVADED

The damage to fishing in the Great Lakes caused by the invasion of the sea lamprey resulted in one of the largest efforts to control a predator (PREH-duh-ter), an animal that hunts another animal for food, ever attempted. The lampreys are believed to have invaded the Great Lakes beginning with the opening of the Erie Canal, which connects the Hudson River and Lake Erie, in 1819 and the Welland Canal, which connects Lake Ontario and Lake Erie, in 1829. The lampreys traveled from the Atlantic Ocean up the Hudson and Saint Lawrence Rivers and through the canals into the lakes. By the 1930s sea lampreys had established themselves in all the Great Lakes. To help solve the sea lamprey problem, the Great Lakes Fishery Commission was established in 1955 by a treaty between Canada and the United States.

CONSERVATION STATUS

Lampreys are not threatened or endangered.

SEA LAMPREY (Petromyzon marinus): SPECIES ACCOUNT

Physical characteristics: Sea lampreys are about 47 inches (120 centimeters) long. The body is grayish brown on top and mottled, or spotted, yellowish brown along the sides.

Geographic range: Sea lampreys live on both sides of the North Atlantic Ocean, in the western Mediterranean Sea, and in the Great Lakes of North America.

Habitat: Sea lamprey larvae live in muddy or sandy freshwater streams. Mature sea lampreys live in open sea or lake water but return to freshwater streams to spawn.

Diet: Sea lamprey larvae feed on plankton and algae. During the early phase of their lives, they live as parasites, attaching to other fishes and sucking out blood and muscle. Sea lampreys do not feed after traveling upstream to spawn.

Behavior and reproduction: Eggs and sperm, or male reproductive cells, develop in sea lampreys during the parasitic (pair-uh-SIT-ik) phase. The lampreys then return to freshwater streams to spawn. The female releases approximately 200,000 eggs, which are fertilized (FUR-teh-lyzed) by sperm released by the male. The adults die soon after spawning.

Sea lampreys and people: In some areas sea lampreys are considered helpful to the environment, and governments are trying to maintain or increase their populations. In the Great Lakes region, however, sea lampreys are ruining fishing, so authorities there are working to control them.

Conservation status: Sea lampreys are not threatened or endangered. ∎