The European brook lamprey (Lampetra planeri, also known as the Brook lamprey and the Western brook lamprey) is a small European lamprey

Lamprey

Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...

 species that exclusively inhabits freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

. This species should not be confused with the North American species Lampetra richardsoni, which is also called the Western brook lamprey.

Description

This lamprey is the most common of the northern European species and is also the smallest. Adult brook lamprey measure from 12-14 cm. The very elongate body is dark blue or greenish above, lightening to yellowish off-white on the sides and pure white below. Like all lampreys they lack paired fins and possess a circular sucking disc instead of jaw

Jaw

The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...

s. They have a single nostril and seven gill openings on either side.

Distribution

Although they are found in small streams, as their name suggests, they are also found in larger rivers throughout northern Europe as well as southern France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, Italy

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, Sardinia

Sardinia

Sardinia is the second-largest island in the Mediterranean Sea . It is an autonomous region of Italy, and the nearest land masses are the French island of Corsica, the Italian Peninsula, Sicily, Tunisia and the Spanish Balearic Islands.The name Sardinia is from the pre-Roman noun *sard[],...

, the Balkans and the upper reaches of the Volga. It is also found in southeast Alaska.

Biology

Unlike most species of lamprey, the adults do not migrate to the sea and do not have a parasitic phase. Adult brook lamprey do not feed and in springtime spawn in gravel close to the soft sediment in which they were previously resident. Adult brook lamprey spawn in small groups and die soon after spawning. The eggs hatch within a few days, after which the young larvae bury themselves in soft sediment with only the mouth protruding. The young lampreys are blind filter feeders, feeding on detritus and other organic matter for three to five years before maturing. Metamorphosis begins in the third or fourth year and is complete after the maturation of the gonad

Gonad

The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon and egg cells are gametes...

s. 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 year.