To create shots that matched up, they had to create key elements by hand. To avoid confusing the audience, they animated parts of 1,200 jellyfish. They were carefully placed in the foreground or middle ground of scenes so the cuts would look natural to the audience. Brown says, “We did those scenes three or four times before we got them right. It was so hard."

The constant movement of jellyfish proved to be a huge challenge for Pixar.

Procedural animation (movements created by computers) was used with the jellyfish. There are three parts to each animal, the bell that can float on the surface, the tentacles, which are the stinging parts that hang down from the outside of the bell, and the "oral arms," which look something like drapes of cloth that hang down from the center of the bell. (The oral arms pull the pray up into the mouth.) While the bell was sometimes hand-animated, computers automatically moved the stuff hanging off of the bell.

To create the computer-controlled movements they had to start by hand animating the basic shapes. Then the technical crew took the basic drawings and created three controls that could be used to adjust movements to get the desired random, natural look. The team could control speed, amount and offset. By adjusting the time and amount of each pulse of different animals, they created the random, natural feel to the scenes. Brown is glad they could get a hand feel to their work without having to animate 77,000 jellyfish by hand.

Procedural animation was also used to get the back and forth movement of the coral that is created by water as it surges and swells, and the movements of anemones were about 95% procedural. The anemone movements are actually similar to the movement of Sulley’s hairs in Monsters, Inc. except gravity is turned upside down and the new effect is called buoyancy.

The expressive faces helped to humanize the fish.

The Hardest Shot
Brown is proud of the work they put into the development of the fish and he believes they created good humans, birds, crabs and other creatures. The accomplishment that he says was the hardest to achieve was being able to do water really well. “Water is the hardest thing to do in computer graphics. In the sequences with the whale there is splashing water going everywhere. It works so well. I don't know if it was more than we could chew, but we certainly bit off a lot. It was enough to make us really nervous going into the picture, but we knew we would come out OK. We expected to figure out a lot of stuff. That is why a lot of us work here. It's a challenge and we want to conquer it.”