The questions this observation poses are as deep and dark as the well. This mysterious fish will have started its incredible life far away in the Sargasso Sea (van Ginneken & Maes, 2006). This is “the earth's only sea without a land boundary”, defined instead by biological characteristics and oceanic conditions to determine its location and extent within the North Atlantic sub-tropical “gyre”, and so named after the abundant presence of Sargassum, a “brown drift algae” (Sargasso Sea Alliance, 2011). It is within this unique ecosystem that the young eel larvae feed, develop and drift using the inherent currents, such as the Gulf Stream to migrate the huge distances to freshwater European and North African rivers. Unusually for fish they can travel over land if necessary, and perhaps it is this ability to move out of the confines of purely aquatic environments enabled it to find its way via groundwater channels into our well. Living for up to 30 years, you can only wonder at the adventures such a creature can have, but I am glad that one of them resulted in it appearing in our garden well - I can only hope that it is able to fulfil its destiny and return eventually to breed in the Sargasso Sea and bring its life full circle.
Sargasso Sea Alliance (2011) [online] About the Sargasso Sea. http://www.sargassoalliance.org/about-the-sargasso-sea [Accessed 21/12/11]van Ginneken, V.J.T, and Maes, G.E (2006). The European eel (Anguilla anguilla, Linnaeus), its Lifecycle, Evolution and Reproduction: A Literature Review. Reviews in Fish Biology and Fisheries, 15 (4): 367-398