Becker, George C. / Fishes of Wisconsin
Lamprey family - petromyzontidae, pp. 199-218 PDF (10.2 MB)
Lamprey Family- Petromyzontidae Five species of lampreys in three genera are known from Wisconsin. Of these, three are parasitic and two nonparasitic. In the United States and Canada, 17 species occur in 3 genera (Robins et al. 1980), and 13 of the species are strictly freshwater forms. A fossil specimen of Mayomy- zon piekoensis was reported from the middle Pennsylvanian Francis Creek Shale of northeastern Illinois (Bardack and Zangerl 1968). Lampreys are scaleless and cartilaginous with funnel-like mouths, often armed with horny teeth. A single, median nostril occurs anterior to the eyes. Seven pairs of gills open to the outside, each by an individual opening. A long single or double dorsal fin is continuous with the caudal fin; paired fins are absent. All adult lampreys show the following traits: (1) In breeding females the anal fin fold is well developed and the tail turns upward, while in the males the anal fin fold is scarcely developed and the tail bends down- ward. (2) The lumen of the intestinal tract becomes nonfunctional and closes in fully mature individuals. (3) Between the time of peak physical development and spawning, the lengths and weights of adult lampreys of both sexes diminish. At spawning time sexually mature individuals are much smaller than they were a few months previously (Vladykov 1951). Adults deposit their eggs in riffles of freshwater streams and then die. Upon hatching, the larval young burrow into silt and sand in quiet water where they filter-feed and grow. After 3 or more years, they metamor- phose into adults during late summer and early fall. The nonparasitic forms spawn the following spring but the parasitic lampreys not until a 199
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