Petromyzon marinus
The destructive effect on the Great Lakes fishing industry caused by the invasion of the sea lamprey is well known. The opening of the Welland Canal in 1829 first gave the species access to the Upper Great Lakes, and it now occurs through the entire system. The maximum size of the landlocked variety appears to be about 762 mm although most individuals are somewhat smaller. The adults live as external parasites of a variety of fish in fresh water. Attaching themselves to the body of the host by means of the sucking disc which is ringed with sharp teeth, a hole is rasped through the victim's skin, and blood and body fluids are thus consumed. Attachment has ranged from 38 to 220 hours in tests. Long considered a delicacy by European diners, the lamprey has, so far, failed to whet North American appetites.
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