The Zorgons are bipedal. However they stoop over, making their true height hard to determine. While stooping they stand 4 or 5 feet tall.
They are stated to constantly be on the hunt for fresh meat, and are shown to ravenously pursue food items (such as humans).
They also posess the ability to flick their tongues at an object from about three feet away, which seems to be a way of catching food. Similar to all snakes on earth they flick their tongues to taste the air.
Zorgons appear to be cold-blooded, as they can be deterred by cold temperatures and were at one point distracted with a burning couch.
Although once having a home planet, they are now an entirely space faring race. Their ships are surprisingly small, about the size of a house, and the book adaptation of the movie states that they are armed with photon beams (presumably an extremely concentrated blast of visible light, as the beams are white in the movie and the heat-loving Zorgons would not want to use infrared).
They are bent on finding materials to burn in order to fuel their ships (an action which led to the destruction of their homeworld).
Zorgons appear to communicate in a language of hisses, growls, and roars.