The Latin name of the sea lamprey is Petromyzon marinus. They resemble an eel in appearance. They were first found in Lake Michigan and belong to the family of 'jaw-less fish'. The larvae is approximately 6 inches in size. The size of the adult lamprey ranges from 20 to 35 inches.
Lampreys can be found in Lake Ontario, Lake Michigan, Lake Superior, the Great Lake, the Atlantic Coast, the Mediterranean Sea, etc. They are born in freshwater areas. Upon turning into adults, they go to the sea. But once it's time for them to breed, they return to their place of birth, to the freshwater body.
The life span of a lamprey can be anything between 3 to 17 years. The life cycle of a lamprey is very similar to that of a butterfly. As is the case with a caterpillar and its metamorphosis into a butterfly, the lamprey buries itself in the mud. This procedure takes around two months―normally from August to October.
In its lifespan, a lamprey is said to consume more than 40 pounds of fish. It feeds on commercially important fish, big and small alike. In the larval stage, it survives on micro-organisms. The lamprey has a mouth shaped like a suction cup. It attaches itself to the body of the fish and sucks blood out of its body. It also preys on the tissues of the fish. A special type of enzyme secreted by the lamprey does not allow the blood of the fish to clot at its wounded portion. It leaves its victim once all the blood and fluid has been sucked out of its body.
The color of the lamprey can vary from black to brown on its back and from light yellow to dull brown on its stomach. It has about 10 to 12 rows of teeth. The innermost row of teeth has the largest teeth.
The male lamprey has two fins, whereas the female lamprey has one. In the same way, there is a difference in the gills of the male and the female lamprey, too. The male lamprey has seven gill slits, whereas the female has two gill pores. When the lamprey is breeding, its back becomes multicolored, and the stomach turns yellow.
The reproduction process starts around winter and continues till summer. A lamprey is said to carry approximately 240,000 ova. It carries stones onto the floor of the water body and lays the eggs there. After breeding it is often found dead. On observing the stomach of the dead lamprey, it has sometimes been found that it has fungal infection in its stomach. Lampreys are unable to recover from the fungal attack.
Since the lamprey preys on the commercial varieties of fish and also disturbs the ecological balance, certain precautionary measures are implemented against it. In some of the lamprey-infected areas, electric currents have been passed, and at the others barricades have been erected. The success rate of these control methods is overwhelming. This activity is a joint exercise between various commissions in the US and Canada.
There are non-parasitic varieties of lampreys as well. Therefore, a clear distinction should be made between the harmful and the harmless ones.