The Prehistoric Piranhas are an ancient prehistoric species of piranha that was long believed to be extinct around 2,000,000 years ago. Unlike the previous piranha versions, instead of genetically engineered piranhas, they are nature.
A tremor has caused the prehistoric piranhas that were trapped underground to be unleashed in Lake Victoria, Arizona and began devouring anyone or anything that they came across. A team of seismologist divers consisting of Novak Radzinsky, Paula Montellano, and Sam with the assistance of Sheriff Julie and Sunny Leone Forester held an underwater expedition to the fissures created by the tremor. Novak speculates that the rift leads to a buried prehistoric lake. Paula and Sam scuba dive to the bottom and discover a large cavern filled with large piranha egg clutches. Both are killed by the piranhas before they can alert the others to the discovery. Novak and Julie find Paula's corpse and pull it onto the boat, capturing a lone piranha. They take the fish to Carl Goodman, a marine biologist who works as a pet store owner. He explains that the piranha that they caught is a prehistoric species, long believed to be extinct, which must have been trapped underground for over two million years where they have grown super-aggressive.
Julie, Novak, along with Deputies Fallon, and Taylor Roberts try to evacuate the beach, but their warnings are ignored until the piranhas begin to attack the tourists. Novak boards a jet-ski to help while Fallon drags people to shore and Julie and Taylor try to get swimmers into the police boat. Julie and Novak commandeer a boat and take it to the sinking Barracuda to save Julie's son Jake and the others still trapped on the boat, while Fallon stays behind to fight off the piranhas with a detached propeller. Julie and Novak reach Jake and attach a rope to his boat. Julie, Danni, Laura, and Zane start crossing the rope, but the piranhas latch onto Danni's hair and ultimately devour her. The others make it to safety, but the rope comes loose. Using Derrick's corpse as a distraction, Jake ties the line to himself and goes to save Kelly. He ties Kelly to him and lights a flare after releasing the gas in a pair of stored propane tanks. Novak starts the boat and speeds away just as the piranhas surround Kelly and Jake. They are dragged to safety and the propane tanks explode, destroying the boat and killing most of the piranhas.
Mr. Goodman calls Julie on the radio, and Julie tells him that they seem to have killed all of the piranhas. Terrified, Goodman tells her that the reproductive glands on the piranha they obtained were not mature, which means that the fish they were fighting were not adults. As Novak wonders aloud where the parents are, a huge piranha leaps out of the water and attacks him.
Role in Piranha 3DD Edit
The piranhas returned in the sequel Piranha 3DD as the main, later secondary antagonists. They still appear as babies instead of full human-sized adults.
A year after the attack on Lake Victoria, an eradication campaign has left the lake uninhabitable for life, and the town itself has been largely abandoned as a result of drying up the lake. Due to the loss of habitat and food source, the piranhas move out to Cross Lake via underground tunnels and sewage pipes, where they manage to find food. In the start of the movie, two farmers are seen looking for their prized cow, only to find it dead. Piranha eggs have been laid into the cow's corpse, and the farmers are killed by the swarm, which even includes the piranha fry.
Shelby and her boyfriend Josh go skinny dipping into the lake, wherein small piranha fry bites her and some secretly swam right into her vagina, wherein she mistakes Josh for doing a painful molestation, which later make her sick on the next day. Ashley and her boyfriend Travis make love inside their van but accidentally trip the handbrake, causing the van to roll into the lake, where they are devoured.
The next day, Maddy, the movie's main protagonist, is consoling a sick Shelby about their missing friends. While sitting on a jetty, they are both attack by a swarm of piranhas and manage to escape them. They kill one and easily recognize it to be the one from the Lake Victoria incident. Along with Kyle & Barry, they pay a visit to Mr. Goodman, who later told them that the piranhas must have found a way through the pipes and underground tunnels. The trio returned to the lake, where they established that the piranhas cannot make their way into the outflow pipes connecting to the lake and waterpark. Unknown to Maddy, her stepfather and co-owner Chet, is secretly pumping water from an underground river into the waterpark.
While Shelby and Josh starts to have sex, a grown piranha crawl's out of Shelby's vagina and bites Josh's penis, forcing him to cut the organ with a knife. Later, when Maddy and Barry visited her, another grown piranha bites its way out of Shelby's stomach. She and Josh are both hospitalized.
Maddy soon discovers Chet's plan and attempts to stop it but was stopped by her stepfather and Kyle, who was secretly working for him. The piranhas make their way into the waterpark, where they start attacking and killing all the lifeguards and waterpark-goers. Deputy Fallon and Drew Cunningham, two survivors of the Lake Victoria incident, who went to the park to overcome their fear of water, witness this and Fallon shows his prosthetic leg, a shotgun, and starts helping the visitors and shooting the piranhas. David Hasselhoff, the park's celebrity lifeguard, saves a kid named David (who was one of the people attacked by a small swarm of piranha fry before the massacre), and becomes pleased that he has become a real lifeguard.
Barry begins to drain the pools to drag the piranhas back; however Maddy, who is rescuing people from the water, gets caught into the suction and dragged down into the bottom of the pool. After Kyle refuses to save her (which later made him insane), Barry, despite being unable to swim, leaps down and brings her to the surface where they kiss.
Big Dave, an employee of the waterpark, pours gasoline into their draining pipes, and throws a lighter into the pipes, thus killing all of the piranhas. The celebration is cut short, when Maddy receives a call from a horrified Mr. Goodman, who informs her that his theory of the piranhas evolving to walk on land, is true while his specimen is seen to have escape its aquarium. The film ends when David videos the Piranha Queen, who in turn ate his head, while some survivors took videos of it and David Hasselhoff comments "Little ginger moron".