Great shot. The one and onlt time I saw a cobra rearing up with its hood spread I found that I had run out of film, and by the time I'd loaded a new one the snake had resumed a normal pose.
Another great shot Alan! Why was the cobra 'hooding' ?
As regards Rob's comment, I had a similar experience with a yawning Pygmy Hippo @ Bristol. Thank god for digital!
I'm not an expert on cobra psychology. I couldn't see any particular reason. These snakes are more alert and active than most snake species and both of them have spells of exploring the enclosure, but they spread their hoods very rarely. It was quite close to the front glass, I didn't get the impression that it was reacting to me or my camera (of course I could be wrong).