  We introduce an active matter model composed of sterically interacting
particles which absorb resources from a substrate and move in response to
resource gradients. For varied ratios of absorption rate to substrate recovery
rate, we find a variety of phases including periodic waves, partial clustering,
stochastic motion, and a frozen state. If passive particles are added, they can
form crystalline clusters in an active fluid. This model could be implemented
using colloidal systems on feedback landscapes and can provide a soft matter
realization of excitable media and ecological systems.
