Having been recognized as a family since 1901, the storks form a well-defined group highlighted by several characteristics both behavioural and morphologic: long legs with the tibiotarsus not covered by feathers; relatively short feet and with small interdigital membranes; 12 primary remiges; 12 secondary remiges; bare parts of the head; oil gland for the feathers, pectoral muscles associated to flying high altitudes; strong beak; feathering predominantly black and white; the young have two layers of fuzz; air sacs under the skin of the neck; loss of the filoplume
; similar social behaviours; uro-hydrosis (behaviour of thermal regulation through defecating on the feet) (HANCOCK; KUSHLAN; KAHL, 1992).
In both eyelids, near the edges, there are modified eyelashes called filoplumes
, for protection and tactile function (MURPHY, 1993; HARRIS et al., 2008; BALDOTTO, 2012).
The normal pelican eye was found to have relative conjunctival hyperemia, absent filoplumes
, iris color ranging from light blue to brown, and a subcircular vertically elongated pupil.