A sun bear weighs roughly 30 to 70 kilograms, yet its tongue is proportionally the longest of any bear. Estimates put the extended length at roughly 20 to 25 centimetres. The bear breaks into a bee nest, a rotten log or a termite gallery with long curved claws, then works the tongue into the space to draw out honey, brood and grubs.
The rest of the animal is built around climbing. The paws are large relative to the body, the soles are hairless for grip and the claws are strongly curved. Sun bears feed and rest in trees, and are the bear most often found well above the forest floor. In the older common name honey bear, the diet is the identifying trait rather than the crescent.
The chest crescent is variable. It ranges from a near-complete horseshoe to a scatter of pale patches, and the pattern is individual enough that researchers have used it for photographic identification. What is not settled is whether the marking carries a signalling function, for instance in threat displays, or is simply variation without a role.