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sea lamprey
The sea lamprey (''Petromyzon marinus'') is a parasitic lamprey found in the northern Atlantic Ocean along shores of Antarctica and North America, in the western Mediterranean Sea, and in the shores of the Great Lakes. It is brown, gray, or black on its back and white or gray on the underside and can grow up to long. After several years in freshwater habitats, the larvae undergo a metamorphosis that allows young postmetamorphic lampreys to migrate to the sea or lakes and start the hematophagous feeding.〔Silva, S., Servia, M. J., Vieira-Lanero, R. & Cobo, F. (2013a). "Downstream migration and hematophagous feeding of newly metamorphosed sea lampreys (Petromyzon marinus Linnaeus, 1758)". Hydrobiologia 700: 277–286. Doi: 10.1007/s10750-012-1237-3〕 Some individuals can start the hematophagous feeding in the river before migrating to the sea,〔Silva, S., Servia, M. J., Vieira-Lanero, R., Nachón, D. J. & Cobo, F. (2013). Haematophagous feeding of newly metamorphosed European sea lampreys Petromyzon marinus on strictly freshwater species. Journal of Fish Biology. 〕 where sea lampreys prey on a wide variety of fish.〔Beamish, F. W. H. (1980). "Biology of the North American anadromous sea lamprey, Petromyzon marinus". Canadian Journal of Fisheries and Aquatic Sciences 37:1924−1943. 〕 The lamprey uses its suction cup-like mouth to attach itself to the skin of a fish and rasps away tissue with its sharp, probing tongue and keratinized teeth. Secretions in the lamprey's mouth prevent the victim's blood from clotting. Victims typically die from excessive blood loss or infection. After 1 year of hematophagous feeding, lampreys return to the river to spawn and die, one year and a half after the completion of metamorphosis.〔
Silva, S., Servia, M.J., Vieira-Lanero, R., Barca, S. & Cobo, F. (2013b). Life cycle of the sea lamprey Petromyzon marinus: duration of and growth in the marine life stage. Aquatic Biology 18: 59–62. doi: 10.3354/ab00488.
〕 Lampreys are considered a delicacy in some parts of Europe, including South-Western France, but are not commonly eaten in the Americas.
==Invasive Species==
Sea lampreys are considered a pest in the Great Lakes region. The species is native to the inland Finger Lakes and Lake Champlain in New York and Vermont. It is not clear whether it is native to Lake Ontario, where it was first noticed in the 1830s, or whether it was introduced through the Erie Canal which opened in 1825.〔(Nonindigenous Aquatic Species Factsheet: Petromyzon marinus ) U.S. Geological Survey (USGS), Nonindigenous Aquatic Species Program (NAS). Retrieved on 2007-08-04.〕 Improvements to the Welland Canal in 1919 are thought to have allowed its spread from Lake Ontario to Lake Erie, and while it was never abundant in either lake, it soon spread to Lake Michigan, Lake Huron, and Lake Superior, where it decimated indigenous fish populations in the 1930s and 1940s. They have created a problem with their aggressive parasitism on key predator species and game fish, such as lake trout, lake whitefish, chub, and lake herring. Elimination of these predators allowed the alewife, another invasive species, to explode in population, having adverse effects on many native fish species. The lake trout plays a vital role in the Lake Superior ecosystem. The lake trout is considered an apex predator, which means that they have no predators of their own. The sea lamprey is an aggressive predator by nature, which gives it a competitive advantage in a lake system where it has no predators and its prey lacks defenses against it. The sea lamprey played a large role in the destruction of the Lake Superior lake trout population. Lamprey introduction along with poor, unsustainable fishing practices caused the lake trout populations to decline drastically. The relationship between predators and prey in the Great Lakes' ecosystem then became unbalanced.
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