Bob Thaves, whose nationally syndicated comic strip "Frank & Ernest" amused newspaper readers for decades with its quirky observations on life, has died of respiratory failure. He was 81.

Thaves died Aug. 8 at Little Company of Mary Hospital in Torrance, said his daughter, Sara Thaves.

His long-running strip stars the happy-go-lucky punsters Frank and Ernest, who travel through time and the universe -- and sometimes change shape -- as they comment on everything from science to world politics.

The strip, which was syndicated in 1972, is distributed to 1,300 newspapers worldwide by Newspaper Enterprise Association and is read by more than 25 million people a day.

Thaves' son, Tom, has collaborated with his father on "Frank & Ernest" since 1997 and will continue to produce it, according to a statement from United Media, whose Newspaper Enterprise Association syndicates the strip.

Sara Thaves said her father's curiosity about the world made his comic strip unique.

Bob Thaves, who held bachelor's and master's degrees in psychology from the University of Minnesota, began cartooning as a child and was published in a college humor magazine at the University of Minnesota.

He went on to cartoon for various magazines and created "Frank & Ernest" while working as an industrial psychology consultant in Los Angeles.

The strip wasn't syndicated until Thaves was 48, and he didn't quit his consulting job until several years later.

"Frank & Ernest" went on to become one of the most popular comic strips in the world, as well as one of the most innovative.

According to United Media, it was the first newspaper cartoon to run in a strip format; the first to use block lettering; the first to use comic book-style digital coloring for the Sunday pages; and one of the first to have its own Web site, in 1997.

The Web site features interactive cartoons as a way to draw Internet readers without losing newspaper fans, Sara Thaves said.