Question

What reptile is the most vocal with some species able to communicate more than 20 distinguishable messages through sound alone?

Answer 1

The most vocal reptile ARE THE CROCODILES.
Crocodiles use different types of calls, smells and water behavior to communicate with one another. Scientists have discovered that some species of crocodiles can pass across up to twenty messages using sound alone. The sounds made can be used to signify threat, distress or it can be used to attract others for courtship purpose. Crocodiles also communicate through smells and through water behaviors.  

Answer 2

The reptile crocodile is the most vocal with some species and is able to communicate more than 20 distinguishable messages through sound alone.