Brook lamprey, Lampetra planeri - Ammocoetes and spawning adults

The young lampreys are blind filter feeders, feeding on detritus and other organic matter for three to five years before maturing. After spending four years as ammocoetes (Larva), these lampreys metamorphose to adults in the fall and spawn the following spring. These small lamprey do not migrate to the sea and do not have a parasitic phase. Brook lampreys spawn in spring and summer in shallow areas of streams and sometimes lakes in gravel close to the soft sediment in which they were previously resident. Both males and females create pits by removing small rocks with their mouths and fanning smaller particles with their tails. The male and female deposit sperm and eggs, simultaneously while intertwined, into the nest.