Vision
Elephant eyes are about 3.8 cm (1.5 in.) in diameter and their vision is moderate. Elephants traverse forests, savannas, and grasslands, primarily orienting with the trunk, as opposed to sight. Ex: There have been documented occurrences of elephant herds being led by a blind member. The complete lack of vision did not hinder the blind member’s ability to fulfill its leadership role.
Elephants have long eyelashes to help avert blowing sand, dirt, and debris from the eyes.
In addition to the upper and lower eyelids, elephants have a “third eyelid” which moves vertically across the eye. These eyelids function to protect the eye when feeding, bathing, and dusting (cooling down). Refer to behavior section.
Some elephants develop a white ring that encircles the iris as they mature. This ring is similar to an age-ring that may develop in humans (as they age) called arcus lipoides, and does not affect vision.
The eyes of an elephant are located on the sides of the head and therefore provide better peripheral vision (angle of vision extending from the sides to the rear), rather than binocular vision (eyes located on the front of the face, in which fields of vision overlap, creating depth perception).
Hearing
Elephants have good hearing, detecting sounds as low as 14 to 16 hz (human low range: 20 hz) and as high as 12,000 hz (human high range: 20,000).
Elephants frequently use infrasonic sounds, which are sounds emitted below the human hearing range, in long-distance communication. Research has shown that elephants are capable of recognizing calls and voices of particular individuals from 1 to 1.5 km (0.6-0.9 mi.) away. Refer to Communication Section.
The ears of the elephant are used to funnel in sound waves from the environment, contributing to its keen sense of hearing.
In general, animals with large heads and wide-set ears are better adapted for hearing lower frequency sounds because the larger skull encompasses longer ear canals, wider tympanic membranes (membrane that separates the middle ear from the exterior), and larger middle ears.
Olfactory
Elephants have a keen sense of smell, detecting water sources up to 19.2 km (12 mi.) away.
Nostrils are located at the tip of the trunk and function in breathing, smelling, and drawing water in to squirt into the mouth. The elephants’ sense of smell is in constant use, with the trunks moving back and forth, detecting new scents and information.
Once a scent is drawn in through thee nostrils, there is a series of seven olfactory turbinals, located in the nasal cavity. Turbinals are curls of bone that have millions of olfactory receptor cells associated with them.
If smelling does not provide enough information, elephants may collect the substance with the trunk. Then the chemical information is passed on to its Jacobson’s organ, a chemical detection unit located in the soft tissue of the upper palate (roof of the mouth). The organ is attached to the oral/nasal cavities and primarily functions to detect the estrus (reproductive) status of a female. This behavior is known as the flehmen response and is characterized by the elephant curling its trunk into its mouth.
Touch
Elephants are very tactile in nature. Elephants use all parts of their body to interact with one another in all forms of behavior, including parental-offspring, playful, aggressive, defensive, exploratory, sexual, and anti-predator.
The trunk is one of the most tactile appendages elephants have. It is used to stroke, touch, explore, caress, or reassure in care-taking and may also be used to slap or block in defense or dominance situations.
The trunk is so sensitive to touch that it is capable of perceiving pressure differences as light 0.25 mm (0.01 in.) in depth, which is equivalent to a light brush against the skin.
The strength of an elephant’s trunk is capable of lifting weights in excess of 250 kg (550 lb.).
Elephant trunks have extensive sensory motor cells, called pacinian corpuscles, that enable them to have a strong sense of touch. The pacinian corpuscles are composed of concentric membranes of connective tissue, similar to the layers of an onion. Between each layer of connective tissue is a slimy gel. When a movement or vibration is detected, the pressure deforms the gel and connective tissue layers of the pacinian corpuscles. This stimulates nerve endings and sends a signal to the brain.
Pacinian corpuscles are also found in the soles of elephant feet, assisting in the detection of seismic vibrations (shaking, vibrating movement of the Earth).
Many animals including elephants survived the Asian tsunami in 2004. It is thought these animals had advanced warning to the tsunami due to their detection of seismic vibrations. The tsunami’s approaching vibrations were detected by the pacinian corpuscles in the elephant’s feet and alerted them to the approaching storm.
