Perception of abrupt temperature decrease by restrained skipjack tuna, Katsuwonus pelamis

1. Decreasing temperature stimuli produced responses and threshold similar to those produced by increasing temperature stimuli in a previous study with skipjack tuna, Katsuwonus pelamis. 

2. Restrained skipjack tuna signaled by deceleration of heart rate that they could perceive abrupt temperature decreases (0·5°C/sec) as small as 1–2°C. 

3. Temperature stimulation of the oral-branchial cavity was more effective in eliciting responses than stimulation of the dorsal, anterior quadrant of the body surface.