Multiple nerve rings coordinate Hydra mechanosensory behavior

Hydra vulgaris is an emerging model organism for neuroscience due to its small size, transparency, genetic tractability, and regenerative nervous system; however, fundamental properties of its sensorimotor behaviors remain unknown. Here, we use microfluidic devices combined with fluorescent calcium imaging and surgical resectioning to study how the nervous system coordinates Hydra′s mechanosensory response. We find that mechanical stimuli cause animals to contract, and this response relies on both the oral and aboral nerve rings. We also find that these nerve rings work together to coordinate spontaneous contractions suggesting that spontaneous behavior and sensorimotor responses converge on to a common neural circuit. These findings improve our understanding of how Hydra′s diffuse nervous system supports sensorimotor behaviors, which is needed to increase the utility of Hydra as a model organism for neuroscience.