Context of Interactions
Elephants are extremely tactile animals. They purposefully touch one another using their trunk, ears, tusks, feet, tail, and even their entire body. Tactile interactions between elephants occur during a broad range of contexts including aggressive, defensive, affiliative, sexual, playful, care-taking and exploratory behavior.
Depending upon how their tusks are employed, elephants may use them to poke another aggressively, to gently lift a baby from a mud wallow, or to express solidarity during a greeting ceremony.
Elephants often use their ears to rub against another affectionately or in play, or their tails to swat another with force or to gently check for the presence of a calf.
An elephant's trunk may be used to caress, reassure or assist a calf, to explore the genitals, mouth or temporal glands of a family member, to touch or explore the body of a dead elephant, to touch or push another in play. In more aggressive or defensive contexts an elephant may use its trunk to slap or to block, or to reach out to another for reassurance when facing a predator. In sexual contexts elephants use their trunks to explore, to test or to control the movements of another.
Elephants use their feet to kick aggressively or playfully, or to explore, caress or assist in an affiliative situation. And an elephant may use its entire head and body to aggressively push or ram another, to rub sensuously against another in a friendly manner or to drive a female in a sexual context.
Details of elephant tactile interactions can be found in ElephantVoices' Gestures Database.
If you are interested in learning more why not check out the following signals on the database: Begging, Bonding-Ceremony, Bunching, Caressing, Consorting, Driving, Dueling, Female-Chorus, Flehmen, Grasp-Tail, Herding-Push, Kick-Back, Mating-Pandemonium, Pushing, Ramming, Reach-Over, Rest-Chin, Sheltering, Sheparding, Social-Rubbing, Soliciting-Guarding, Sparring, Spinning, Tail-Swat, Test-Genitals, Test-Mouth, Test-Temporal-Gland, Trunk-Twining, Tusk-Clicking, Tusking. Or try searching on the following words: "touch" and "touching".
Sense of Touch
When we think of our human sense of touch we think immediately of our sensitive hands. Likewise, when we imagine an elephants sense of touch we think first of their prehensile trunk, for it is with the trunk that elephants most often touch others. An elephant is capable of using its trunk to perceive differences in the width of grooves as small as 0.25 mm.
The extensive sensorimotor specializations of the trunk allow delicate manipulations of both large and small objects and contain some of the most sensitive tissue ever studied. Called Pacinian corpuscles these specialised cells can pick up minute vibrations. These corpuscles are comprised of concentric membranes of connective tissue, like the layers of an onion, with the gaps between filled by a slimy gel. Movements or vibrations deform these layers, stimulating nerve endings and sending a signal to the brain.
Pacinian corpuscles are found in other mammals too, for instance in human fingertips, but they are particularly densely packed in the elephant's trunk. Elephants' ability to detect seismic vibrations suggests that similar cells are also present in the soles of the feet. You can read some more about pacinian corpuscles here.