Abstract
Nervous systems have evolved to function consistently in the face of the normal environmental fluctuations experienced by animals. The stomatogastric nervous system (STNS) of the crab, Cancer borealis, produces a motor output that has been studied for its remarkable robustness in response to global perturbations. Changes in environments are often complex and multifactorial. We studied the robustness of the pyloric network of the STG in response to simultaneous perturbations of temperature and pH. We compared the effects of elevated temperatures on the triphasic pyloric rhythm at control ,acid ,or base pHs. In each pH, recordings were made at 11 0 C, and then the temperature was stepped up in 2 0 C, increments, until the rhythms became disorganized, or "crashed". As the temperature was raised, there were few obvious differences between the pyloric burst frequencies and phase relationships between the conditions, until close to the crash temperatures. Nonetheless, the temperatures at which the rhythms were disrupted were lower in the two extreme pH conditions. This indicates that one environmental stress can make an animal less resilient to a second stressor.