NEW YORK (Reuters) - British rock legend David Bowie's career will take a dive next year -- as he joins the cast of the popular underwater cartoon SpongeBob SquarePants for a guest appearance.

Bowie said on his Web site blog that he would be the voice of a character called Lord Royal Highness on the Nickelodeon network's hit children's cartoon series next year.

"It's happened. At last. I've hit the Holy Grail of animation gigs," Bowie, 59, said on his Web site (www.davidbowie.com/bowie/journal/index.php) on Wednesday.

"We, the family, are thrilled. Nothing else need happen this year, well, this week anyway."

Bowie has a six-year-old daughter, Alexandria, with his wife, the model Iman.

The singer has had a long list of acting credits, appearing in the films "Merry Christmas Mr. Lawrence" and "Labyrinth," as well as in the BBC sitcom "Extras" with comedian Ricky Gervais in which he played an exaggerated version of himself.

SpongeBob SquarePants has been a hit with children and adults around the world since its 1999 debut.

SpongeBob is a friendly sponge who lives with his pet snail Gary in a pineapple under the sea.