The southern cassowary is the third biggest bird after the ostrich and emu. Compared to the single wattled northern cassowary, it is slightly larger and has two wattles, which hang loosely from its neck.   

It resembles a dinosaur with its helmet-like spongy casque that grows throughout life. The casque may be used for pushing through undergrowth, regulating temperature, and detecting the calls of other cassowaries.

Like the northern cassowary, this flightless fowl can become aggressive when cornered or provoked. It defends itself with dagger-like claws deployed in a formidable kick.

Cassowaries have the unfortunate reputation of being the most dangerous bird alive, known to harm or even kill humans. However, this reputation is likely exaggerated as cassowaries are not overly aggressive, and attacks are rare.