Sci&Tech Writer Tom Martin introduces us to the Lamprey
In 2015, The Guardian reported that, after 200 years, the ‘living fossils’ known as Lampreys had returned to British rivers such as Ouse, Trent and Derwent.
Older than dinosaurs themselves, Lampreys are a jawless fish with a toothed, funnel-like mouth. They are referred to as “nine-eyed eels” in folklore due to their seven external gill slits, single nostril and single eye.
There are about 38 known living species of Lamprey. The most commonly known are the parasitic carnivorous species which feed by latching on the flesh of other fish with their concentric rows of sharp teeth and boring through scales to suck their blood. Eighteen recorded species of lampreys feed in this way however, known as ‘micro-predation’. Of those eighteen carnivorous species, half hunt exclusively in saltwater environments, migrating to freshwater only to breed.
The other half that do live entirely in freshwater will almost never attack a human unless starved. The vast majority of the pure-freshwater Lampreys are non-carnivorous, and instead live off reserves acquired through filter feeding as larvae.
In the Great Lakes of North America, sea lampreys are now considered an invasive species. They have no natural predators in that environment and target commercially valuable species such as the lake trout. Complicated and expensive systems of lampricides, chemicals which specifically target the species, are being deployed in an effort to control populations to more manageable levels.
In fact, you’re probably more likely to eat a lamprey than you are to be eaten by one! Lampreys have been a dish enjoyed by ancient Romans, through to the medieval aristocracy. Lampreys are still even sold and eaten across Southwestern Europe, as well as parts of Asia and Scandinavia. Before you decide on Lampreys for your Christmas Dinner however, know Lamprey mucus is highly toxic. For this reason, King Henry I is said to have died after, against his physicians’ orders, overindulging in the delicacy.
So next time you fancy some waterside walking just remember these king-killing prehistoric horrors are swimming once again in a river near you.