Godfrey-Smith (2001, p. 6) claims that "plants and bacteria do exhibit some capacities for flexible response to environmental conditions, using environmental cues to control development and metabolism." As an example, he cites the lac operon system in E. coli bacteria:

These bacteria can respond to a change in local food type through processes in which the availability of a nutrient affects the regulation of genes which code for enzymes able to digest that nutrient.

From the foregoing description, it should be clear that we are not dealing with flexible behaviour here, but with behaviour which can be described by a fixed mathematical function, whose input variables are the local concentrations of different nutrients (lactose and galactose).

Plants' ability to adjust to changes in lighting

Another example of flexibility cited by Godfrey-Smith is the ability of plants to adjust to different lighting conditions:

For example, many plants can determine not just that they are being shaded, but that they are being shaded by other plants. This is done by detecting the wavelength properties of the reflected light. The plants respond to shading by growing longer shoots... (2001, p. 7).

Singing strategies in crickets

Carruthers (2004), while rejecting (rightly in my view) a mentalistic interpretation of the singing behaviour of crickets, describes it as flexible. According to my definition, such behaviour is fixed:

It turns out that even flexibility of behavioral strategy isn't really sufficient for a creature to count as having a mind, indeed. For innate behavioral programs can have a conditional format. It used to be thought, for example, that all male crickets sing to attract mates. But this isn't so; and for good reason. For singing exposes crickets to predation, and also makes them targets for parasitic flies who drop their eggs on them. Many male crickets adopt the alternative strategy of waiting silently as a satellite of a singing male, and intercepting and attempting to mate with any females attracted by the song. But the two different strategies aren't fixed. A previously silent male may begin to sing if one or more of the singing males is removed... (2004)

Here, the output behaviour for a male cricket (wait or sing) can be described as an invariant function of two variables: (a) its "attractiveness rating" and (b) the number of attractive males nearby.