Complex sentence: Savannahs may also "hiss"--a Serval-like hiss quite different from a domestic cat's hiss, sounding more like a very loud snake hiss, that can be alarming to humans not acquainted to such a sound coming from a cat.
Split into simpler sentences: Savannahs may also "hiss"--a Serval-like hiss quite different from a domestic cat's hiss, sounding more like a very loud snake. It can be alarming to humans not acquainted to such a sound coming from a cat.