Animals

Lampreys

by Marcia Malory

Lampreys (Hyperoartia) are jawless fish.

A lamprey has a long body and looks like an eel.

Lampreys are sometimes called lamprey eels.

A lamprey has a round mouth that is surrounded by suckers with horny teeth.

Its tongue is covered with teeth as well.

Lampreys, photo by Drow_male

Some species of lamprey are parasites. They suck the blood and bodily fluids of other fish.

A lamprey will use its suckers to attach itself to a host and then use its teeth to cut through the host's skin.

It will secrete an anticoagulant (a substance that prevents blood from clotting) into the blood of its host.

A lamprey can cause a small fish to bleed to death.

Fish that are bitten by lampreys can develop fatal infections at the site of the bite.

All species of lamprey, those that are parasitic and those that are not, will eat small invertebrates.

Lampreys live in both the ocean and in fresh water, in cold and temperate regions.

Those that live in the ocean migrate to fresh water in order to spawn (breed).

Fish that usually live in the ocean but spawn in fresh water are anadromous.

A lamprey can use its suckers to help itself travel upstream. It will hold itself in place against the current by sticking itself to a rock.

Lampreys have been regarded as pests in the Great Lakes of North America, where they feed on species like trout, whitefish and herring and have caused damage to fisheries.

They are not native to the Great Lakes.

Lampreys are native to the Atlantic Ocean and moved to the Great Lakes when canals were built to connect the Atlantic Ocean with the Great Lakes.

A species that moves to a new habitat and has a negative effect on that habitat is known as an invasive species.

Physical Characteristics

Adult lampreys range from about 5 inches to over 3 feet long.

Lampreys differ from hagfish, the only other type of living jawless fish, in that lampreys have spinal columns (backbones) while hagfish do not.

Animals with spinal columns are known as vertebrates.

A lamprey is a vertebrate, but a hagfish isn't.

Lampreys have skulls. Therefore, lampreys are craniates.

A lamprey's skull and spinal cord are made of cartilage.

The spinal column of a lamprey is less developed than the spinal columns of other vertebrates.

A lamprey's spinal column consists of small pairs of cartilage, which are known as arcualia.

Every lamprey has a notochord - a flexible rod supporting its body.

Lampreys are the only vertebrates that keep their notochords throughout their lives.

Other vertebrates lose their notochords when they are embryos.

All chordates have notochords at some time in their lives. A lamprey is a chordate. All vertebrates are chordates, but not all chordates are vertebrates.

Lampreys do not have scales. Their skins are covered with mucus, or slime.

This slime makes it difficult for humans to extricate lampreys from fishing nets.

A lamprey has large eyes on each side of its head and one nostril on top of its head.

It has seven gills on each side of its body. The gills are enclosed in pouches.

Lampreys can pump water directly in and out of their gills, without using their mouths, so they can breathe while they are feeding or while they are using their mouths to hold themselves in place on rocks.

A lamprey does not have paired fins, but it has two dorsal fins (back fins) and a caudal fin (tail fin).

Lifecycle

Unlike hagfish, which may be hermaphrodites, lampreys are either male or female.

Lampreys practice external fertilization.

They are oviparous. This means that eggs are laid outside of the female's body.

Lampreys lay their eggs in nests, which consist of depressions in gravel at the bottom of bodies of fresh water.

They use their suckers to move pebbles around when they are building their nests.

Lampreys undergo metamorphosis.

A lamprey larva is known as an ammocoete.

An ammocoete looks very different from an adult lamprey.

It has no suckers and no teeth.

Ammocoetes have only rudimentary eyes. They are thought to be blind.

The gills of lamprey larvae are not enclosed in pouches.

Ammocoetes bury themselves in sediment at the bottom of bodies of water. They feed by filtering their food from the water. They eat small organisms, such as algae, and organic debris.

A lamprey can remain in its larval stage for up to seven years before it metamorphosizes into an adult.