Northern Brook Lamprey

Northern Brook Lamprey
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Cephalaspidomorphi
Order:	Petromyzontiformes
Family:	Petromyzontidae
Genus:	Ichthyomyzon
Species:	I. fossor
Binomial name
Ichthyomyzon fossor Reighard and Cummins, 1916

The Northern Brook Lamprey, Ichthyomyzon fossor, is a lamprey found in North America throughout the Great Lakes Watershed. There are limited populations within the Mississippi watershed.

Lampreys are long, slender fish-like animals, lacking lower jaws, which results in a downward facing mouth. Its body has no scales.Lampreys have clearly visible muscle segments (myomeres) between the gills and anus, a continuous dorsal fin, an oval shaped caudal fin, a single nostril, and seven gill pores.

Physical description

As with all lamprey species, the northern brook lamprey spends the majority of its life as a worm-like ammocoete. The ammocoete (5 mm-20 cm) is clear with a pigmented head when small (<5 cm) but becomes a dark brown as it matures. Ammocoetes have a pigmented eye spot located in the head, that can detect light and dark. After metamorphosis from the ammocoete into the juvenile stage the lamprey becomes a silver with dark gray countershading on top and clear fins. The mouth develops at this time and teeth (used to identify species) develop on the oral disk. The eye develops from the eyespot as well during metamorphosis. As the juvenile matures into the adult the body swells as the gonads are developed.

Life cycle

Adults spawn in the spring in the headwaters of streams. The males (aided by females) construct small nests by picking up pebbles with their mouths and moving them to form the rims of shallow depressions. The sticky eggs are deposited in the nest and adhere to the sand and gravel. Multiple adults may spawn in the same nest, and multiple males may spawn with the same female. As with all lamprey adults die after spawning.

When they first hatch embryos remain in the nest for up to one month before they mature into ammocoetes. Ammocoetes leave the nest and seek out slow flowing sandy areas, where they burrow and begin feeding. Ammocoetes live burrowed for 3-7 years, feeding on microscopic plant and animal life and detritus (decaying matter). Mature ammocoetes will begin to metamorphosis in the late summer through the fall. Juvenile brook lamprey cannot eat, since they have a nonfunctional intestine, and only live for four to six months.

References

• Reighard and Cummins, Description of a new species of lamprey of the genus Ichthyomyzon, 1916

External links

• www.rook.org
• http://www.seagrant.umn.edu/newsletter/2002/03/lake_superiors_native_lampreys.html