BARCELONA, Spain – Sony unveiled a new waterproof phone that can take ultra-high-definition video. Nokia introduced three Android smartphones aimed at emerging markets. And Lenovo announced one with an all-glass exterior.

Yet the spotlight Monday was on Samsung, which announced a successor to its flagship Galaxy S4 smartphone. The Galaxy S5 will feature a heart-rate monitor, a fingerprint sensor for security and a sharper camera with faster auto focus.

Samsung's glitzy announcement during the Mobile World Congress wireless show in Barcelona, Spain, made it more difficult for other phone makers to get noticed. Samsung had several times the attendance of either Sony's or Nokia's event Monday. An orchestra opened Samsung's event as blue spotlights moved up and down the aisles.

"It's increasingly difficult to get attention for your mobile device in a very crowded marketplace," said Dan Hays, U.S. wireless advisory leader at the consulting firm PwC.

It's even more difficult when one of the competing devices comes from Samsung Electronics Co., which announced the new phone a day after it unveiled two new computerized wristwatches, the Gear 2 and Gear 2 Neo. Samsung also announced a fitness band on Monday. Apple is the only company that might be able to overshadow Samsung, but it isn't attending or announcing anything at the show.

Roger Entner, an analyst with the Recon Analytics research firm in Boston, said the S4 and its predecessor, the Galaxy S III, have helped Samsung surpass iPhone maker Apple Inc. as the world's largest smartphone maker. According to Gartner, Samsung had a 31 percent market share last year, compared with 16 percent for Apple. No other company had more than 5 percent.

Attendees at the Mobile World Congress, the world’s largest mobile phone trade show in Barcelona, Spain.

Sony Mobile President Kunimasa Suzuki said that with Apple and Samsung so dominant, the real battle is for No. 3. He said that means marketing that is focused by country and product line. "It doesn't mean we just directly compete with the big giants," he said.

Despite its muscle, Samsung will have to give people a reason to upgrade. There's a notion that phone improvements these days are incremental rather than innovative. Samsung tried to shatter that notion by highlighting features not found in other phones. That includes a heart-rate sensor to complement its upcoming wearable fitness devices. The S5 is also among the first to have a fingerprint sensor for security, even though that's already in Apple's iPhone 5s.

But even phones with spectacular features and designs might still go unnoticed if they aren't from Apple or Samsung.

"There's lots of attention lavished on them because they have the most to lose," Hays said.