Final answer:
Three living organisms that commonly inhabit islands include moose, various aquatic species categorized as plankton, nekton, and benthos, and specialized animals like marine iguanas or diverse bird species, as well as various forms of plant life.
Step-by-step explanation:
When identifying which three living organisms inhabit an island, one should consider the varied ecosystems present, such as those involving moose, aquatic organisms, and the diversity of life represented in different environments. For terrestrial organisms, moose serve as a clear example of island inhabitants. In aquatic environments, we find diverse species, with organisms living in oceans and those living around freshwater sources like lakes, streams, rivers, and ponds. Aquatic life can be categorized into plankton, nekton, and benthos, representing different modes of living and moving in the water.
On islands, especially ones like the Galápagos, we may find specialized species like marine iguanas that have adapted to both land and sea environments. Birds are also common island inhabitants; two genera observed on an island might show different adaptability after environmental changes. Alongside these animal species, various forms of plant life, such as grasses, shrubs, and trees, contribute to the organismal diversity.