Ichthyomyzon fossor
    Northern Brook Lamprey

Northern Brook Lamprey

Flora, fauna, earth, and sky...
The natural history of the northwoods



  • Ichthyomyzon, from the Greek, "fish to suck", a reference to the feeding habits of the parasitic members of the genus.
  • fossor,
  • Common name from its habitat and range
  • Other common names include:


  • Kingdom Animalia
    • Phylum Chordata, animals with a spinal chord
    • Subphylum Vertebrata, animals with a backbone
      • Superclass Agnatha
      • Class Cephalaspidomorphi
      • Subclass Cephalaspidomorpha
        • Order Petromyzontiformes
          • Family Petromyzontidae, lampreys
            • Genus Ichthyomyzon


  • A slender, primitive, eel-like fish
  • Length to 6"
  • Color
    • upper body dark grey or brown
    • sides grey or silver
    • belly orange or silver
    • posterior part of the tail dark grey or black
    • base of the dorsal fin tan
    • eye bluish
  • Body
    • skin leathery, without scales
    • segments clearly defined, numbering XX?? between the last gill slit and the anus.
    • dorsal fin continuous, not divided into two distinct fins
    • caudal fin oval
    • cartilaginous skeleton (boneless)
  • Head
    • ends in a funnel
    • mouth a jaw-less, sucking disc which is narrower than the body width where the gill openings are found.
    • teeth, located in the funnel, small and poorly developed; weak and in clusters
    • gill pores seven in number, in a straight line immediately behind the eye
    • single nostril between the eyes
Ammocoete length range from 130 to 170mm while adults range from 115 to 170mm in length.

 A single large tooth with two blunt cusps small mouth opening, and six to 11 blunt teeth are arranged in a line below the opening. Rows of smaller single teeth are situated around these larger teeth. The body is scaleless, with the first and second dorsal fins joined and connected to the tail fin. Except for an anal fin, sometimes connected to the tail fin, there are no other fins.


  • Easily distinguished from other Northwoods fishes by its eel-like shape and sucking mouthparts.
  • Distinguished from the other native lamprey by its brown color, small size, continuous dorsal fin, and bicuspid teeth.


  • The secretive nature of its habits makes knowledge of its distribution rather vague and undetermined.
  • St. Lawrence River drainage west to Lake Winnipeg, south through Wisconsin, Minnesota, Iowa, to southern Missouri, Kentucky.
  • Native to the Red River, Rainy River, and Superior drainages in northern Minnesota.


  • Clean headwaters of creeks and small rivers with coarse gravel to rock bottoms located in once glaciated terrain.
  • Low water levels are a threat to immature lamprey
  • Pollution and siltation can damage spawning areas and thus pose a threat to successful reproduction
  • Programs to destroy sea lampreys have affected northern brook lamprey populations, since many individual were destroyed, thus leading to a reduction in the population; this species has low fertility, and so has had difficulty recovering from the sea lamprey destruction programs


  • Larval stage feeds on minute plants, animals, and bits of organic matter
  • Adult digestive system non-functional, indicating that no food is consumed from fall until spring.


  • The earliest known lampreys, Mayomyzon, are from the Pennsylvanian Period, about 300 million years ago. They are thought to be related to an extinct group of jawless fishes, the ostracoderms, which flourished earlier.



  • Spawning adults gather in the shallow water of creeks and small rivers during May and June. The sucking mouth is used to remove stones up to six inches in diameter, to create a spawning depression among coarse gravel rocks and beneath larger rocks. The bodies of spawning individuals are generally vertically oriented. Several days after spawning, the adults die. The sticky mass of eggs hatches in 15 to 30 days, releasing small larvae (ammocoetes) which make "U"-shaped burrows in the silt and sand bottom of quieter areas of the stream. Ammocoetes develop a hooded mouth structure and feed on small, one-celled plants and animals. After three to four years, teeth develop with in the hooded mouth and the digestive tract degenerates. Newly transformed adults are about five to six inches long. Sexual maturity is attained just before the spawning period.
  • Non-parasitic, living 3-5 years as a filter feeding larvae (ammocoete) in the bottom sediments of streams before transforming into a non-feeding adult in mid-summer to late fall. The following spring the adult lamprey spawns completing its life cycle.


  • The native lamprey species of the genus Ichthyomyzon should not be confused with the exotic and destructive Sea Lamprey (Petromyzon marinus), which wreaked havoc with native game fish in the Great Lakes before vigorous control measures brought it to check. The native lamprey have evolved with, and live in balance with, their host populations.
  • Identified as Vulnerable in Ontario
  • Listed as a species of special concern in Minnesota, New York
  • Listed as Threatened in Kentucky,
  • Listed as Endangered in Illinois, Ohio, Pennsylvania, Vermont
  • Watershed management is necessary to maintain the undisturbed habitat and water quality required by this species. Larvicides used to control parasitic sea lamprey populations must not be applied in northern brook lamprey habitat.
  • Rare throughout its limited Great Lakes and disjunct midwestern range.


  • Lampreys, a general article from the Tree of Life

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Last updated on 13 November 1999