Here’s this week’s practice question for a thrilling passage about fish coloration– put Chris’s science passage tips to use! We’ll be posting the answer tomorrow, good luck!
Protective coloration is common among animals. Some animals are countershaded for camouflage. For example, the next time you pass a fish market, look at the specimens laid out for viewing. Fish are nearly always darker on top than on the bottom. The selective theory of camouflage has long been favored by some ichthyologists, who believed that countershading reduces the contrast between the shaded and unshaded areas of the body when the sun is shining on the fish from overhead and lessens its vulnerability to predators. However, the discovery that the Nile catfish is reverse-countershaded—that is, its dorsal (upper) surface is light and its ventral (lower) surface is dark—turned this theory on its head.
However, enterprising ichthyologists saved the selective theory of camouflage by observing that the Nile catfish swims upside down, primarily to feed from the surface of the water. Some ichthyologists speculate that the Nile catfish also swims upside down for protection.
The passage provides information on each of the following EXCEPT:
- etiology of countershading
- etiology of reverse-countershading
- feeding habits of countershaded fish
- selective theory of camouflage
- protective coloration of animals