LOOK into a swordfish’s eye and you’ll see a burning desire to go hunting. For these ocean predators heat their retinas, a trick that allows them to see prey better.
Most fish are cold-blooded, but swordfish can maintain the temperatures of their eyes and brains at between 19 and 28 °C, even in nearly freezing water. Now Kerstin Fritsches of the University of Queensland in Australia and colleagues have found out one reason why. The swordfish’s retina is extremely sensitive to temperature, reacting five times faster to visual stimuli for every 10 °C increase in temperature (Current Biology, vol…
