Zoology 10th Edition by Stephen Miller,John Harley

Exercise 4

The lateral-line system of fishes detects electrical currents in the surrounding water. Neuromasts detect water displacement or disturbances. Sound waves in aquatic animals, such as fish, travel through the body of a fish because the fish's body is composed primarily of water and the sound passes through the water and stimulates otoliths, which transduce the sound. In terrestrial animals, sound waves in air must transition to the fluid in the inner ear where hair cells bend, causing an action potential. Nerve endings are called nociceptors. Severe heat, cold, irritating chemicals, and strong mechanical stimuli stimulate these receptors, which send a message to the brain for interpretation as pain. A rattlesnake has a pit organ between each eye and nostril that detects heat and allows the snake to locate warm-body prey in the dark. Taste and smell chemoreceptors detect chemicals from outside the body; olfactory receptors detect thousands of different odors. The five taste categories in humans are sweet, sour, better, salty, and umami. Photoreceptor rods and cones contain a pigment that is activated by light and then causes an action potential that reaches the occipital lobe of the brain.
The lateral-line system of primary terrestrial adult amphibians is lost during metamorphosis from aquatic larval to adult stages. Why is the lateral-line system not useful to these adult amphibians?