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Hello, fellow ocean enthusiasts! Let us introduce you to the newest residents of the Aquarium—vampires… well, the sea lamprey. It’s an easy mistake to make and you’ll find out why in today’s Deep Sea Diary.

A primitive fish, lamprey existed 360 million years ago and have remained relatively unchanged over evolutionary time. Just like sharks, the skeleton of a lamprey is composed of cartilage—the same material that is found in the bridge of your nose. Their long, slender body has no scales, fins, or gill covers. To breathe, sea lampreys rely on seven pairs of gill pores, or small holes located behind their eyes. Lamprey also lack jaws, instead possessing a distinct sucker mouth and sharp, radially oriented teeth used to latch onto prey. Their rasping ‘w’ shaped tongue can pierce a fish’s scales and flesh with ease, allowing the lamprey to feast on their blood.

A close-up image of the Lamprey mouth
Above is a close-up of the lamprey mouth. Despite the appearance of their radially-oriented teeth, it is actually their tongue (shown by the arrow) that is used to burrow into the flesh of other fish.

Young lamprey hatchlings, also known as ammocoetes, emerge in the early summer months. Drifting with the current, they settle further downstream in the sediment at the bottom of streambeds. For the first several years of their life, lamprey will remain in these streambeds and filter feed on microorganisms that float by. After sufficient growth, the lamprey will undergo a metamorphosis—changing into its more recognisable parasitic form and migrating into the ocean, ready to find unsuspecting fish to latch onto. Lamprey will remain in this phase for up to 18 months, at which point they migrate back to their native streams to spawn and end their lifecycle.

Image of a sea lampreys

Despite their name, sea lampreys have been found—and caused great havoc—in the Great Lakes. First discovered in Lake Ontario in the 1830s, they likely arrived from the ocean through shipping canals. For a long time, sea lampreys were confined to Lake Ontario, as Niagara Falls prevented them from spreading. It wasn’t until nearly eighty years later, when the renovation and deepening of the Welland Canal allowed them to by-pass The Falls. With this new access, their populations exploded!

By 1938, sea lampreys had invaded all of the Great Lakes. Larger, ocean dwelling fish are more resilient to the parasitic lamprey attacks, however smaller lake fish often perish. Only an estimated one in seven fish attacked by a lamprey will survive. For over a decade, sea lampreys devastated fish populations in our Great Lakes.

Since the 1950s, to control lamprey populations, scientists regularly use chemical treatments to kill lamprey larvae before they enter their parasitic adult phase. Don’t worry—it’s harmless to other fish. The success of these programs have resulted in a drastic decline of sea lamprey

populations—a 90% reduction in some areas! Sea lamprey populations are now under control, however other invasive species programs have not had such luck.

If you want to learn more about invasive species and what you can do to prevent their spread swim over to our Invasive Species 1, 2, 3 Deep Sea Diary.

A big tank you to the Great Lakes Fishery Commission for our newest, blood-sucking additions. Swim by the new Shipwrecks exhibit to see these unique fish yourself!

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