MorFish

About the Sea Lamprey

About the Sea Lamprey

Fossil discoveries suggest that lamprey have lived from the late Silurian and Devonian periods, 450 million years ago. In Europe we have three species which are in ascending size: the brook; river; and sea lamprey. By far the largest of the three is the sea lamprey Petromyzonmarinus which can grow to an enormous 100cm long and weigh in at 2.5kg.

Lampreys are quite distinct from other fish in the British Isles. In fact they are not really fish at all as they have no lower jaws, but instead the mouth is surrounded by a round, sucker-like disc that in adults has a set of strong rasping teeth which is used to attach themselves onto fish and other prey from which they parasitise. Fish on the other hand have fixed upper jaws and hinged lower jaws. On first appearances lampreys resemble eels, but actually with a little further investigation you soon realize that the similarities end there. These ancient creatures have no bones at all, but instead the 'skeleton' is made up of powerful and flexible cartilage and they only have one nostril which sits on top of the head, just behind the eyes. Seven holes that start behind the eye and run down each side of the body are gills, but they have no flap or operculum to act as a cover.

The sea lamprey’s life cycle is similar to that of salmon where they spend their adult stages in the sea but migrate into rivers to spawn. Little is known about its time at sea, as it not only uses estuaries, but also frequents much deeper waters. Sea lampreys are protected as Annex II species under the EU habitats Directive.