Pulpy plunge.

This guy has gotten into a juicy mess. Last summer, he joined thousands of people as they hurled tomatoes at each other at an annual tomato-throwing festival in Spain.

This isn't your average food fight: In preparation for the festival, six trucks carried 130 tons of tomatoes to Bunol. Locals covered their shop fronts with sheets of plastic, hoping to keep the indoors from becoming a sauce pit. Meanwhile, participants suited up in grungy clothes to ready themselves for a serious tomato spattering.

What makes the tomato a top choice for the annual food battle? Its succulent qualities come from the fact that a tomato is a fruit, or a structure that contains the seeds of a flowering plant, says Jay Scott, a tomato breeder at the University of Florida. To ensure that the seeds develop unscathed, a tomato's exocarp (outer skin) forms a barrier to hungry insects.

Besides keeping the seeds safe, a tomato's thin covering holds in its juicy contents. For Bunol's combatants, that means the tomato can sail through the air like a water balloon. Then--splat!--the skin bursts and the fruit's seeds and gel-like liquid shoot out.

During the two-hour tomato battle, these ripe missiles turned the town's streets into rivers of red sauce. Good thing the tomato slingers weren't decked out in their best clothes: These giant berries are packed with the red pigment lycopene (LY-cuh-peen). As the fruit ripens, its color deepens. "And as it gets redder, the fruit tends to get juicier," says Scott. That way, racoons and other fruit eaters will be drawn to the plump, eye-catching tomatoes. When the animals snack on the fruit, the tomato's seeds pass through their digestive tracts and into their waste. Seed dispersal accomplished!

The bright color and squishy feel of the tomatoes also attracted the festival's 20,000 revelers, who launched more than 100,000 tomatoes--seeds and all.