These robots are part animal, part machine

Another option is to use more robust cells as actuators. Here at Case Western Reserve University, we've recently begun to investigate this possibility by turning to the hardy marine sea slug Aplysia californica. Since A. californica lives in the intertidal region, it can experience big changes in temperature and environmental salinity over the course of a day. When the tide goes out, the sea slugs can get trapped in tide pools. As the sun beats down, water can evaporate and the temperature will rise.