Mathematical model reveals how a pit viper is able to find its dinner in the dead of night

# Mathematical model reveals how a pit viper is able to find its dinner in the dead of night

In the animal kingdom, many species use their surroundings to navigate and find food. For example, an eagle can spot a fish in a river, a bear can smell food from two miles away, and a platypus can detect electric impulses in the water. Then there are pit vipers, which use powerful infrared sensors near their nostrils to hunt for prey in the dark by sensing temperature changes, comparable to the sensory abilities of humans. Yale physicists have developed a new mathematical model, outlined in a study published in the journal Proceedings of the National Academy of Sciences, to explain how pit vipers achieve this remarkable feat.

Isabella Graf, a postdoctoral fellow in physics at Yale’s Faculty of Arts and Sciences (FAS), and Benjamin Machta, an assistant professor of physics at FAS, propose that pit vipers possess a biological mechanism that amplifies small signals and transmits them to the brain with high fidelity. Their mathematical model uses statistical physics and information theory to understand how the incoming temperature signal from a pit viper’s individual ion channels collectively affects the neuronal response. The researchers discovered a “bifurcation” point near which the neuronal response qualitatively changes, enabling the snake’s brain to extract almost as much information about temperature as if it could read out the measurement from each individual sensor and then average them together perfectly to get one accurate measurement. This mechanism allows pit vipers to detect milli-Kelvin changes in temperature with their sensory organ, despite living in environments with dramatic temperature fluctuations between day and night.

The study also explains how pit vipers maintain their thermal sensitivity amid sweeping shifts in temperature between day and night. The researchers incorporated a “feedback” feature into their mathematical model, which protects the overall sensitivity of the snake’s sensory system throughout temperature swings.

Graf and Machta believe that their findings may have applications beyond the pit viper’s nocturnal hunting abilities. They suggest that similar feedback and design principles might exist in other sensory systems that need to detect tiny signals in varying environments.