negative regulation of response to external stimulus +
pigment accumulation +
polyphenic determination, influence by environmental factors +
positive regulation of response to external stimulus +
reflex +
regulation of response to external stimulus +
response to environmental enrichment
response to external biotic stimulus +
response to extracellular stimulus +
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an extracellular stimulus.