Yes it is true, elephant calves do suck their trunks, says elephant expert Kate Evans . As in all young mammals, an elephant calf's sucking reflex - prompting it to drink from its mother's breast- is strong. When a youngster is not feeding, sucking its trunk may provide comfort.
Newborn elephants have little control over their trunks, and must learn how to use them.
They practise by exploring their environment - touching fellow herd members, their surroundings and themselves.
They must then master the use of their trunks for feeding. With more than 50,000 individual muscle units in the trunk - a fusion of the upper lip and nose - it's a complex skill to learn.
Though trunk-sucking is more common in the early stages of life, elephants of all ages do it - even big, old bulls - usually when they are feeling nervous or unsure.
Sometimes an elephant that appears to be sucking its trunk is actually using it to smell, placing the tip inside its mouth after touching or sniffing dung or urine to assess pheromones produced by other elephants.
Learn more about elephants including what ivory is and whether it is unique to elephants and whether elephant graveyards really do exist.