spend two to three years in marine habitats before making the return trip to spawn. Statistics As ammocoetes, identification of these animals beyond genus level (Lampetra) is difficult because of their close similarity to brook lamprey. They average 30 cm in length as adults, and some may be considerably smaller (20 cm), but in each case they are distinctly larger than adult brook lamprey (12–14 cm). They are generally 150 g in mass, and their maximum life span is roughly 10 years. See also Lamprey pie References Further reading Lampetra Freshwater fish of Europe Animal parasites of fish Least concern biota of Europe Fish described in 1758 Taxa named by Carl Linnaeus