The meaning space of an organism is its Umwelt as distinguished from its environment (what appears to surround it from a human observer’s point of view). However, you can say this just as well by using ‘environment’ in place of Umwelt and ‘external world’ in place of environment. For instance, Richard Lewontin in his 1983 article on ‘Gene, Organism and Environment’:
How do I know that stones are part of the environment of thrushes? Because thrushes break snails on them. Those same stones are not part of the environment of juncos who will pass by them in their search for dry grass with which to make their nests. Organisms do not adapt to their environments; they construct them out of the bits and pieces of the external world. This construction process has a number of features:
(1) Organisms determine what is relevant. While stones are part of a thrush’s environment, tree bark is part of a woodpecker’s, and the undersides of leaves part of a warbler’s. It is the life activities of these birds that determine which parts of the world, physically accessible to all of them, are actually parts of their environments. Moreover, as organisms evolve, their environments, perforce, change.— (Oyama, Griffiths and Gray 2001, 64)