Much field research had to be performed to accurately make this picture. Wild Hydras were fed "volunteers" to examine and study how the hydra swallowed its prey. Of course, with any scientific endeavor, the tests had to be repeated a few dozen times to ensure the data collected was accurate! (Much to the test subject's dismay and the hydra's excitement)

Summing it up, I watched a few videos numerous times to see exactly where the bulges were in its neck at any given time :P
Pretty sure the only way I'll ever be able to get good enough video footage of it (Many HQ ones just go around killing the poor thing, or have the camera blocked from viewing the bulges) would be getting the game myself, and that isn't gonna happen.

Another thing to note is where the hydra's show up. The initial encounter is easy enough to get to, and has the bonus of being in a well lit and neutrally-lighted area, to better bring out the hydra's texture. The downside is there's not much room for the hydra to move about, and as a result it's harder to get better shots from multiple perspectives.

The second encounter requires playing pretty much the entire game (Uh-huh, like i'd do that) to get to, or most of the game and some dumb luck if you want to settle for the less visually appealing "Arch Hydra". The upside is there's tons of room for the hydra to move about, and you can get some lovely dynamic shots of it. The downsides are getting there in the first place, and the dim lighting. This is a MAJOR con with most videos that involve feeding this hydra, since the low video quality makes the dim lighting even worse.

Anyway, just a quick sketchie. I know I can do better than this, but alas. I tried drawing someone in the mouth, but bleh. It was proving too difficult and was killing my motivation, so I dropped it and moved on ^^