Katy tweeted the snap above of herself transformed into shimmering mermaid just weeks after Lady G performed as mythological sea creature on French TV's Le Grand Journal. Even earlier, leaked photos showed that Gaga initially toyed with using the concept on her Edge Of Glory music video.

But taking the contest one step further, Perry's pic shows her planking on a piling beneath a bride. "PROPER planking FTW! #itswhatArielwoulddo," Katy boasted on Twitter.

The tweeted pic has Gaga's so-called "creative director" Laurieann Gibson in a snit. "Proud of my artist #1 in the world @Ladygaga her vision& passion,'' Gibson tweeted a few hours after Perry's photo went out. "Even though they try to steal a tail there's only 1 Mermaid, Swim On!!!"

For the record, Gibson and Little Monsters: Katy also appeared as a mermaid at the 2009 Life Ball in Vienna, held to raise money for those afflicted with HIV and AIDs.