Fig. 1. The four morphs of Arctic charr Salvelinus alpinus L. found in Lake Thingvallavatn, Iceland. The specimens of piscivorous (PI), large benthic (LB), planktivorous (PL) and dwarf benthic (DB) morph illustrated are close to the maximum body size found. The distinct head and fin morphology and the different colouration of the different morphs used in their classification is readily apparent.