Sea Lamprey – Petromyzon marinus

Sea lamprey. Petromyzon marinus. Photo from US EPA.

Parasitic, jawless ‘vampire’ fish with toothy suction mouth

The sea lamprey (Petromyzon marinus) is one of the most wonderfully weird freshwater creatures we’ve featured in the Cabinet in some time.  Translated from a mixture of Greek and Latin, lamprey means ‘stone licker‘, most likely due to the fish’s tendency to hug the bottom of the rivers of Atlantic Europe and America that it inhabits with its curious sucker-like mouth (see the amazing close up photo above).  Unlike many other lampreys, for the sea lamprey, this fearsomely toothy mouth serves a deadly purpose: to suck the blood of unwitting fish.

Sea lampreys attached to an American Lake Trout. Image: Wikipedia

Sea lampreys attach their wraith-like bodies to the skin of passing fish (such as the lake trout, above), gripping with rows of tiny sharp teeth embedded in their suction-cup mouth and probing with a keen tongue to drain blood from the host’s body.  The lamprey’s fantastically odd characteristics: its eel-like, jawless body, the suction-cup mouth and its anadromous behaviour (i.e. lives in both the sea and freshwater), have led some scientists to contest that it should even be described as a ‘fish’ at all!

Sea lampreys in an aquarium. Image: Wikipedia

Despite these fearsome, wonderfully odd adaptations, within a healthy ecosystem (for example in the River Usk in the U.K.), the sea lamprey is important to the complex web of life, both as a predator and as prey (e.g. to birds such as herons, and to people – indeed King Henry I of England (1068–1135) was said to be so fond of the taste of lamprey that he died after eating ‘a surfeit’ of them!).  However, accidental introductions of the sea lamprey to the Great Lakes of America through shipping canals and container ships in the 1800s have caused an ecosystem crisis as the lamprey feasts on native lake trout, as described in the video below.

Millions of dollars have been spent in trying to eliminate the sea lamprey from the Great Lakes.  In 2009, under the headline “Sex smell lures ‘vampire’ to doom” (!), the BBC reported on conservation managers in the Great Lakes trialling the use of a laboratory version of a male sea lamprey pheromone, released into waterways to trick ovulating females into swimming upstream into traps.  However, the picture is not so rosy for the sea lamprey on the other side of the Atlantic Ocean.  Over the last century, sea lamprey numbers have declined dramatically in northern Europe, with no current breeding sites known of in the Baltic region.   As a result, conservation efforts are aimed at increasing sea lamprey populations in the region.

Isn’t it fascinating how perceptions and management of this much-maligned, incredible fish can vary so widely on different sides of the Atlantic? A true freshwater curiosity!

More information on the sea lamprey:

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