Sense Organs
To help them see in the dim light, mid- water fishes characteristically have eyesthat are not only large but unusually sensi-tive. Large, light-sensitive eyes also occurin squids, shrimps, and other groups.Some midwater fishes have developed
tubular eyes
(Fig. 16.13), a complex visualsystem that is almost like having two pairsof eyes. Tubular eyes give very acute visionin the direction that the eyes are pointed