24 Q 4

Describe the life cycle of sea lanpreys, Petromyzon marinus and the history of their invasion of the Great Lakes.

Life Cycle~1. Adults leave the ocean to swim up streams to prepare for spawning. 2. Spawn in winter/spring in North America. 3. Males begin nest building and are later joined by females. 4. Males use oral discs and body vibrations to form an oval depression. Eggs are shed into the nest and the male deposits sperm upon them (oviparious). 5. Adults die soon after spawning. 6. Eggs hatch in two weeks as larvae called ammocoetes. 7. Take up suspension feeding life while growing for -37 years then metamorphose into adults. ~A.J.E.

Invaded Great Lakes west of Niagara falls after Welland Ship Canal was built in 1829. Took nearly 100 years to really begin invasion though. Spread rapidly and caused lots of damage, especially to commercially important fishes. Decline now after peaking in 1951 due to low food and control measures. ~A.J.E.

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