Common eel  (Anguilla anguilla)

Catadromous: Migratory behaviour of some fish that spend most of their lives in freshwater, but migrate to the sea to breed.
Larvae: 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.
Metamorphosis: An abrupt physical change from the larval to the adult form.
Plankton: Aquatic organisms that drift with water movements; may be either phytoplankton (plants), or zooplankton (animals).

1. IUCN Red List (November, 2008)
   http://www.iucnredlist.org
   
2. Fish, J.D. and Fish, S. (1996) A Student's Guide to the Seashore. Second Edition. Cambridge University Press, Cambridge.
   
3. FishBase (January, 2003)
   http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=35&genusname=Anguilla&speciesname=anguilla
   
4. Strathclyde University (January, 2003)
   http://www.strath.ac.uk/Departments/Civeng/research/cemr/eel_study.htm
   
5. Silver eel: Integrative Zoology, University of Leiden (January, 2003)
   http://www.fishbiology.net/silvereel.html
   
6. Estimation of the Reproductive Capacity of European Eel (EELREP) (January, 2003)
   http://www.fishbiology.net/eelrep.html
   
7. Burnie, D. (2001) Animal. Dorling Kindersley, London.