${var^^}
Raises or lowers the case of the whole value — or just the first letter.
The caret lifts, the comma lowers: ${var^^} returns the value in uppercase, ${var,,} in lowercase. A single symbol — ${var^}, ${var,} — touches only the first letter.
It is a recent arrival: bash 4.0. In zsh the same case change lives in the flags ${(U)var} and ${(L)var}. To compare user input caselessly, ${resposta,,} normalizes before the case.
$ especie="Apis mellifera"
$ echo ${especie^^}
APIS MELLIFERA
$ echo ${especie,,}
apis mellifera