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The sea lamprey (Petromyzon marinus) is a parasitic lamprey native to the Northern Hemisphere. It is sometimes referred to as the "vampire fish". In its original habitats, the sea lamprey coevolved with its hosts, and those hosts evolved a measure of resistance to the sea lampreys. It was likely introduced to the Great Lakes region through the Erie Canal in 1825 and the Welland Canal in 1919 where it has attacked native fish such as lake trout, lake whitefish, chub, and lake herring, Sea lampreys are considered a pest in the Great Lakes region as each individual has the potential of killing 40 pounds of fish through its 12–18 month feeding period. Description The sea lamprey has an eel-like body without paired fins. Its mouth is jawless, round and sucker-like, and as wide or wider than the head; sharp teeth are arranged in many concentric circular rows. There are seven branchial or gill-like openings behind the eye. Sea lampreys are olive or brown-yellow on the dorsal and lateral part of the body, with some black marblings, with lighter coloration on the belly. Adults can reach a length of up to 120 cm (47 in) and a body weight up t 2.3 kg (5.1 lb). Etymology The etymology of the genus name Petromyzon is from petro- "stone" and myzon "sucking"; marinus is Latin for "of the sea". Distribution and habitat The species is found in the northern and western Atlantic Ocean along the shores of Europe and North America, in the western Mediterranean Sea, the Black Sea, and as an invasive species in the Great Lakes. They have been found at depths up to 4000 meters and can tolerate temperatures of 1–20 °C (34–68 °F). In North America, they are native to the Connecticut River basin in the United States, the inland Finger Lakes and Lake Champlain in New York and Vermont. The largest European populations of sea lampreys are located throughout the southwestern areas of Europe (north-central Portugal, north-northwest of Spain, and west–southwest of France). These countries also support the main fisheries of the species. Ecology Sea lampreys are anadromous; from their lake or sea habitats, they migrate up rivers to spawn. Females deposit a large number of eggs in nests made by males in the substrate of streams with moderately strong current. Spawning is followed by the death of the adults. Larvae burrow in the sand and silt bottom in quiet water downstream from spawning areas and filter-feed on plankton and detritus. After several years in freshwater habitats, the larvae undergo a metamorphosis that allows young, post-metamorphic lampreys to migrate to the sea or lakes, and start the adult hematophagous method of feeding. Some individuals start hematophagous feeding in the river before migrating to the sea, where sea lampreys prey on a wide variety of fish. 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. A fluid produced in the lamprey's mouth, called lamphredin, prevents the victim's blood from clotting. Victims typically die from excessive blood loss or infection. After one year of hematophagous feeding, lampreys return to the river to spawn and die, a year and a half after the completion of metamorphosis. Lampreys are considered a delicacy in some parts of Europe, and are seasonally available in France, Spain, and Portugal. They are served pickled in Finland. Physiology Due to its lifecycle that switches between fresh and salt water, the sea lamprey is adapted to tolerate a wide range of salinities. Cell membranes on the surface of the gills are major contributors to ionoregulation. Changes in membrane composition influence the movement of different ions across the membrane, changing amounts of components to change the membranes' environment. As the larvae (called ammocoetes) move towards the oceans, the ratio between saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) in the gills shifts towards higher amounts of SFA, as they affect the fluidity of the membrane, and higher levels of SFA lead to a decrease in permeability compared to PUFA. Lamprey ammocoetes have a relatively narrow range of salinity tolerance, but become better able to withstand wider ranges of salinity concentrations as they reach later stages of life. Tight regulation of Na/K-ATPase and an overall decrease in expression of H-ATPase assists in regulating the lamprey's internal fluid and ion balance as it moves to areas of higher salinity. Lampreys also maintain acid-base homeostasis. When introduced to higher levels of acids, they are able to excrete excess acids at higher rates than most other saltwater fishes, and in much shorter times, with the majority of the transfer of ions occurring at the gill surface. Sea lampreys parasitize other fishes for their diet, including elasmobranchs such as sharks and rays, which have naturally high levels of urea in their blood. Urea is toxic to most fishes in high concentrations, and is usually excreted immediately. Lampreys are able to tolerate much higher concentrations than most other fish and excrete it at extremely high rates, obtained from ingested blood. Trimethylamine oxides present in ingested elasmobranch blood aid in counteracting the detrimental effects of high urea concentration in the lamprey's bloodstream as it feeds. Immunology Two presumptive apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC)s expressed in lymphocytes—CDA1 and CDA2—have been discovered in P. marinus. Genetics The genome of Petromyzon marinus was sequenced in 2013. This sequencing effort revealed that the lamprey has unusual guanine-cytosine content and amino acid usage patterns compared to other vertebrates. The full sequence and annotation of the lamprey genome is available on the Ensembl genome browser. The lamprey genome may serve as a model for developmental biology and evolution studies involving transposition of repetitive sequences. The lamprey genome undergoes drastic rearrangements during early embryogenesis in which about 20% of the germline DNA from somatic tissues is shed. The genome is highly repetitive. About 35% of the current genome assembly is composed of repetitive elements with high sequence identity. Northern lampreys have the highest number of chromosomes (164–174) among vertebrates. Two genes important to immune function—CDA1 and CDA2—were first discovered in P. marinus and then found to be conserved across lampreys. See §Immunology above. Invasive species Sea lampreys are considered a pest in the Great Lakes region. 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 was not clear as of 2007. 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 Supe.... Discover the Leanne Boehm popular books. Find the top 100 most popular Leanne Boehm books.