Animators love to make realistic-looking creatures. Duplicating the look of most vertebrates — whether people, mice or marmosets — is a well-established art. Making an invertebrate, like a jellyfish, look realistic is another matter.
Karen Liu, Jie Tan, and Greg Turk from the Georgia Institute of Technology presented a paper at SIGGRAPH 2012, detailing a new method of building animated characters, one that makes it a lot easier on the animator, and a lot less expensive.
Instead of treating bodies as frameworks of bones, they programmed "muscles" that would change a character's shape. They also included an algorithm that assumes the mass of the character stays the same even though its shape changes.
Ordinarily, an animator might use the "skeleton" of a character as a basis for movement. While walking, an animated person's feet remain the same size, just like in real life. Or, if he is standing still but gesturing with a hand, the feet remain stationary, as will most of the leg. That wouldn't happen with an amoeba or some other blob-like creature — as one side moves, it pulls on the opposite side, elongating it, for example.
The computing technique allowed the programmers to make characters that move according to higher-level goals, which means they didn't have to specify every single movement and every portion of the creature. That cut the programming time and effort a lot. To demonstrate they made a video of dancing letters of Jell-O. See it below.
Image: Georgia Tech
via Georgia Tech