River lamprey  (Lampetra fluviatilis)

Anadromous: In fish: those species that spend most of their lives at sea but migrate to fresh water to spawn.
Larval: Of the stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Vertebrates: Animals with a backbone.

1. UNEP-WCMC (March, 2002)
   http://quin.unep-wcmc.org
   
2. Environment Agency. (1998) Species Awareness leaflet Number 5. Lamprey. Environment Agency, Bristol.
   
3. IUCN Red List (August, 2009)
   http://www.iucnredlist.org
   
4. Conserving Natura 2000 Rivers: River, Brook and Sea Lamprey (September, 2008)
   http://www.english-nature.org.uk/lifeinukrivers/species/lamprey.html
   
5. Fishbase (March, 2002)
   http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=4480&genusname=Lampetra&speciesname=fluviatilis
   
6. JNCC (September, 2008)
   http://www.jncc.gov.uk/protectedsites/sacselection/species.asp?FeatureIntCode=S1099
   
7. Cihar, J. (1991) A Field Guide in Colour to Freshwater Fish. Aventium publishing, Prague.
   
8. The Life in UK Rivers Project (October, 2002)
   http://www.english-nature.org.uk/LIFEinUKRivers/index.html