European Brook Lamprey, Lampetra planeri
The European Brook Lamprey (Lampetra planeri), known also as the Brook Lamprey and the Western Brook Lamprey, is a small European lamprey species that exclusively inhabits freshwater. This species shouldn’t be confused with the North American species, Lampetra richardsoni, which is also called the Western Brook Lamprey.
This species is the most common of the North European species in addition to being the smallest. Adult specimens measure from 12 to 14 centimeters. The very elongate body is a dark blue or greenish color above, lightening to yellowish off-white on the sides and pure white below. Like all lampreys, they lack paired fins and have a circular sucking disc opposed to jaws. They have one single nostril and seven gill openings on either side.
Although they can be found in small streams, as their name suggests, they can also be found in larger rivers throughout northern Europe in addition to southern France, Italy, Sardinia, the Balkans, and the upper reaches of the Volga. It can also be found in southeast Alaska.
Unlike most lampreys, the adults don’t migrate to the sea and don’t have a parasitic phase. The adults do not feed and in the springtime spawn in gravel close to the soft sediment in which they were formerly resident. The adults spawn in small groups and die soon after they spawn. The eggs hatch within a few days, after which the young larvae bury themselves in the soft sediment with only the mouth sticking out. The young are blind filter feeders, feeding on detritus and other organic matter for three to five years before they mature.
Metamorphosis begins in the third or fourth year and is complete after the maturation of the gonads. The eyes and suction disk also develops during this time, while the intestinal tract degenerates and loses its function. The full transformation can take up to a whole year.
Image Caption: European Brook Lamprey, Lampetra planeri. Credit: Ra Boe/Wikipedia (CC BY-SA 3.0)