Marketers have been focused for years on targeting millennials, now it's time to start focusing on even younger consumers. Get ready for the 'post-millennials.'

During the opening session of the Ad Age Digital Conference in San Francisco, top marketing executives from Nickelodeon and Target detailed the emerging, unique behavior of the youngest consumers. They presented a case study on the joint campaign around the revamp of the Teenage Mutant Ninja Turtles franchise.

Born around 2005, the 'post-millennial' is a digital native, constantly connected to a host of devices. Tablet ownership in households with children aged six to eleven is rising rapidly, with kids focused heavily on gaming and entertainment, said Pam Kaufman, CMO and president of consumer products at Nickelodeon. "This is an audience we better know very, very well," she said.

The television network has branched out into a series of digital channels. Accompanying the Teenage Mutant Ninja Turtles film, distributed with Viacom, Nickelodeon leaned on a suite of marketing platforms from mobile apps to cupcakes. "This has become a global consumer goods powerhouse," said Ms. Kaufman.

Kids do not surrender their devices once they enter a store, either. Ninety-eight percent of 'post-millennials' use their devices while they shop at Target, said Rick Gomez, the retailer's SVP, brand and category marketing. He referred to his young consumers as "the demanding enthusiast." Target has built a campaign tailored to mobile shopping for the franchise.

Marketing to families, too, means that campaigns much shift to the youngest members, both speakers said.

"Kids are making the decision about where to go on vacation, what cars to buy," Ms. Kaufman said, eliciting chuckles from the audience. "You guys are laughing because you know it's true."