Baby Toucan

The legs of the toucan are strong and rather short. Their toes are arranged in pairs with the first and fourth toes turned backward. The majority of toucans do not show any sexual dimorphism in their coloration, the genus Selenidera being the most notable exception to this rule (hence their common name, "dichromatic toucanets"). However, the bills of female toucans are usually shorter, deeper and sometimes straighter, giving more of a "blocky" impression compared to male bills. The feathers in the genus containing the largest toucans are generally black, with touches of white, yellow, and scarlet. The underparts of the araçaris (smaller toucans) are yellow, crossed by one or more black or red bands. The toucanets have mostly green plumage with blue markings.
The colorful and large bill, which in some large species measures more than half the length of the body, is the hallmark of toucans. Despite its size, the toucan's bill is very light, being composed of bone struts filled with spongy tissue of keratin between them. The bill has forward-facing serrations resembling teeth, which historically led naturalists to believe that toucans captured fish and were primarily carnivorous; today it is known that they eat mostly fruit. Researchers have discovered that the large bill of the toucan is a highly efficient thermoregulation system, though its size may still be advantageous in other ways. It does aid in their feeding behavior (as they sit in one spot and reach for all fruit in range, thereby reducing energy expenditure), and it has also been theorized that the bill may intimidate smaller birds, so that the toucan may plunder nests undisturbed. Also, the beak allows the bird to reach deep into tree-holes to access food unavailable to other birds, and also to ransack suspended nests built by smaller birds. However, as there is no sexual dimorphism in coloration it is unlikely to be a sexual signal.
A toucan's tongue is long (up to 14–15 cm, or 6 inches), narrow, grey, and singularly frayed on each side, adding to its sensitivity as an organ of taste.
A structural complex probably unique to toucans involves the modification of several tail vertebrae. The rear three vertebrae are fused and attached to the spine by a ball and socket joint. Because of this, toucans may snap their tail forward until it touches the head. This is the posture in which they sleep, often appearing simply as a ball of feathers, with the tip of the tail sticking out over the head.