Transcript Sea Lamprey
(Petromyzon marinus) Ms. Sneha Singh Department of Zoology, DAVCG, Yamunanagar. External Features Physical Characteristics They have no scales Adults can range from 5 to 40 inches long Rings of needle sharp teeth form the “O” of the mouth Habitat Anadromous: Migrating from salt water to spawn in fresh water. In its natural habitat, the sea lamprey lives in the open ocean. It migrates into freshwater to spawn. Native Habitat Sea lampreys are native to the coastal regions of both sides of: North Atlantic Ocean, Labrador Canada to the Gulf of Mexico Florida on one side Norway (Iceland and the Barents Sea) Western Mediterranean Sea Northern Africa Some Prehistoric Facts Lampreys developed from jawless fishes that swam through prehistoric waters five hundred million years ago. The jawless fish then died in what later became a coal mine, south of what later was Chicago. Reproduction In the spring and early summer, adult sea lampreys ascend streams and rivers to spawn. The males construct depressions that serves as nests or redds along sandy bottoms with gravel or small stones. The female sea lamprey can lay from 30,000 to100,000 eggs and the male fertilizes them after which, both adults drift downstream and die. Lamprey Nest “Their nests, which are very conspicuous, look more like art than anything in the river. " ~Henry David Thoreau~ Lamprey Life Cycle Fortunately, only one year in the life of a sea lamprey is spent in parasitic feeding. They are unusual in having a complex life cycle, whereas most fish have a simple life cycle. A. Sea lampreys go through an extended larval phase before metamorphosing into the bloodsucking parasitic phase. Each summer and fall there is one group of parasitic sea lampreys actively feeding in the Great Lakes. B. The next spring, that group leaves the lake and migrates into tributary streams where they must build nests in clean gravel with flowing water. C. Each female spawns an average of 60,000 to 70,000 eggs. Life Cycle Cont’d D. After hatch, the larvae drift downstream to areas with slower currents and sand/silt bottoms. There, they establish permanent burrows and enter a larval stage varying in duration from 3 to 10-ormore years. E. Larvae lack eyes and the oral disc. Living concealed in their burrows, they are harmless and filter microscopic material from the water for food. When they reach lengths of 120 mm or more, some individuals begin metamorphosis in mid summer. F. During metamorphosis they develop eyes, the oral disc, and changes in their kidneys that (in their native range) would allow them to enter the salt water of the Atlantic Ocean. That fall or the following spring, they instead enter the Great Lakes to feed parasitically on fish that summer and fall, and mature and spawn the next spring—completing their life cycle. Sea lampreys only spawn once and then die after spawning. Life Cycle of the Sea Lamprey • • • http://www.seagrant.umn.edu/ais/sealamprey_battle Average of 5-8 years Eggs hatch and larvae feed at the bottom of streams and lakes on debri and small plants (3-6 years) Turn into parasitic adult for 12-20 months Origins and Travel of the Sea Lamprey • • • • • • • Coastal areas of Atlantic 1919 - canal built to bypass N. Falls and allows access 1921 - Lake Ontario for the first time 1936 - Lake Michigan 1939 - invasion of all great lakes 1940-1950 Population explosion 1955 - creation of the Great Lakes Fishery Commission http://dnr.wi.gov/org/caer/ce/eek/critter/invert/lamprey.htm Improved Control Methods Treatment with TFM is currently still the primary tool for control. Ineffective and laborintensive screen weirs have been replaced with low-head barriers that block sea lampreys but allow jumping fish to pass. Thank You…