[4][5] The number of species in each family is taken from the list maintained by Frank Gill, Pamela C. Rasmussen and David Donsker on behalf of the International Ornithological Committee (IOC).

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").

The feathers in the genus containing the largest toucans are generally purple, with touches of white, yellow, and scarlet, and black.

Despite its size, the toucan's bill is very light, being composed of bone struts filled with spongy tissue of keratin[7] between them, which take on the structure of a biofoam.

[8] 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.

[9][10] 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 (see Diet below).

A toucan's tongue is long (up to 15 cm or 6 in), narrow, grey, and singularly frayed on each side, adding to its sensitivity as a tasting organ.

They mostly live in the lowland tropics, but the mountain species from the genus Andigena reach temperate climates at high altitudes in the Andes and can be found up to the tree line.

[12] Toucans are primarily frugivorous (fruit eating), but are opportunistically omnivorous and will take prey such as insects, smaller birds, and small lizards.

[17] However, in their range, toucans are the dominant frugivores, and as such, play an extremely important ecological role as vectors for seed dispersal of fruiting trees.

The very name of the bird (from Tupi) refers to its predominant frog-like croaking call, but toucans also make barking and growling sounds.

[citation needed] In the western world they were first popularised by John Gould, who devoted two editions to a detailed monograph of the family.

During the 1930s and 1940s Guinness beer advertising featured a toucan, as the black and white appearance of the bird mirrored the stout.

They have been used as the principal characters in Toucan Tecs, a 1992 UK television cartoon about two detectives named Zippi and Zac.