Tentacled snakes turn C-starts to their advantage and predict future prey behavior

Abstract

Fish are elusive prey with a short-latency escape behavior--the C-start--initiated to either the left or right by a "race" between 2 giant Mauthner neurons in the fish brainstem. Water disturbances usually excite the ipsilateral neuron, which massively excites contralateral motor neurons, resulting in a rapid turn away from striking predators. Here, it is reported that tentacled snakes (Erpeton tentaculatus) exploit this normally adaptive circuitry by feinting with their body, triggering the Mauthner cell that is furthest from their head milliseconds before a ballistic strike is initiated. As a result, fish that were oriented parallel to the long axis of the snake's head most often turned toward the approaching jaws, sometimes swimming directly into the snake's mouth. When strikes were instead directed at fish oriented at a right angle to the snake's head, snakes anticipated future fish behavior by striking to where fish would later be if they escaped from the snake's body feint, which fish usually did. The results provide an example of a rare predator taking advantage of a prey's normally adaptive escape circuitry and suggest that the snake's sensory-motor system is adapted to predict future behavior.