Elegance on water

The beautiful swan gliding around the lake,
Swans are birds of the family Anatidae within the genus Cygnus.
The swans' closest relatives include the geese and ducks. Swans are grouped with the closely related geese in the subfamilyAnserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae. 
There are six living and many extinct species of swan; in addition, there is a species known as the coscoroba swan which is no longer considered one of the true swans. Swans usually mate for life, although "divorce" sometimes occurs, particularly following nesting failure, and if a mate dies, the remaining swan will take up with another. The number of eggs in each clutch ranges from three to eight.
The English word swan, akin to the German Schwan, Dutch zwaanand Swedish svan, is derived from Indo-European root *swen ('to sound, to sing'). Young swans are known as cygnets or as swanlings; the former derives via Old French cigne or cisne(diminutive suffix et 'little') from the Latin word cygnus, a variant form of cycnus 'swan', itself from the Greek κύκνος kýknos, a word of the same meaning. An adult male is a cob, from Middle English cobbe (leader of a group); an adult female is a pen.