What organ do cassowaries use for breathing?

Answer 1

The Southern Cassowary (like all birds) has a pulmonary system where the lungs and the mouth are all connected.

Answer 2

Cassowaries are birds: thus, they use lungs for breathing, as all birds do.

Answer 3

Like all birds, southern cassowaries have a pulmonary system, whereby the lungs, nose and mouth are connected.