Raccoons usually wet their food before eating it. People often think that they are washing their food, but that is not the reason for the habit. Scientists speculated in the past that raccoons suffered from chronic dry mouth or a shortage of salivary glands, but studies disproved those theories.
Raccoons wet their food to gather more sensory information about it from nerve endings in their paws. Moistening food enhances a raccoon’s understanding of what it is eating. Unlike humans, who gather most of their information about the world around them from their sense of sight, raccoons gather information primarily through their sense of touch.
When a raccoon touches an object, it gathers nearly two-thirds of its sensory data from cells that interpret various types of sensations from touch. Their paws have four to five times more mechanoreceptors than most other mammals. This enables raccoons to hold, manipulate, and interpret objects as well as humans and other primates.
Water is important to a raccoon’s sense of touch. It increases the receptiveness of the nerve endings in the paws and substantially increases the raccoon’s tactile senses. A study was conducted in 1986 and published in the journal Somatosensory Research that studied 136 raccoons and found that wetting the skin on their paws dramatically improved their sensitivity.
The way raccoons use water to enhance their sense of touch is similar to the way humans use light to see. When light enters the eye, it increases optical nerve responsiveness and makes it easier to see. When water touches a raccoon’s paws, it improves tactile nerve responsiveness and provides more information about food. This is important since raccoons eat so many things, including things found in trash cans, and need to be able to figure out what is and is not edible.