Of the five senses (touch, taste, smell, sight, hearing), touch probably functions in the most similar way for animals on land and underwater. Touch is very important in close social interactions. For underwater animals, the sense of touch may also provide important information about water currents and the motions of nearby animals.

Touch is very important to marine mammals, such as these manatees. Photo courtesy of South Florida Water Management District, a regional state agency working to restore the Everglades, http://www.sfwmd.gov

The senses of taste and smell enable animals to detect chemical compounds; they serve very similar functions. The underwater environment presents very different opportunities for these senses. Chemical particles travel much more slowly in water than in air. Thus, except for very short range effects, it is likely that the sense of smell is largely used to detect the trail of chemicals left behind by a moving animal (or the "trail" created by stationary animal in a current), rather than the chemicals that drift away from a stationary animal.