What is indicated by both shells of mussels that shut and open when water is thrown on them?

The behavior of mussels opening and shutting their shells in response to water is a strong indicator that they are alive. Living mussels have a natural reflex to react to changes in their environment, and one of those reflexive actions is to close their shells when water is applied. This action is often a response to potential threats or changes in water conditions.

When mussels are alive and healthy, they will actively filter water and will respond to stimuli. If they were dead, they would not exhibit such reactions; their shells would remain open or closed permanently without responding. This behavior also denotes that they are capable of regulating their internal environment, which is a fundamental indicator of life.

Understanding these biological responses is crucial for assessing the health and viability of mussels in aquatic ecosystems, particularly in the context of managing and monitoring aquatic invasive species (AIS) within Wyoming waters.