The eight women form two parallel lines in the deep end of Riverside Park Pool, gracefully spinning in time to the chants of director Emily Burtt.
"One, two, three, four," she counts. "Nice toes. Keep those toes real pointy."
Soon, the colorful caps, lizard tails and starfish suits on the swimmers make it clear this isn't your grandmother's water aerobics.
The swimmers are rehearsing a scene from It's a Wonderful Species, this year's water ballet from Baltimore-based performance group Fluid Movement. Opening today, the show uses synchronized swimming and on-land acting to take a lighthearted and fantastical look at Charles Darwin's effort to publish his 1859 treatise Origin of Species.
For what is sometimes a controversial subject, it's really all comedy. The lizards-and-starfish scene portrays the mating rituals of the animals on the Galapagos Islands in the context of a high school prom. Serious, it's not.
The show's plot is loosely modeled on the movie It's a Wonderful Life, except here the angel Clarence is replaced by a crass monkey trying to convince Darwin (Steve Beall) that he's sitting on a gold mine and should publish the book after 18 years of waiting.
"Even I could write it - if I had thumbs," jokes Adam Krandle as the monkey.
Krandle suggests that if someone else publishes a history before Darwin does, the world could be reading that dinosaurs were obliterated by the beat-poetry war tactics of the cavemen - which performers gladly act out.
The show flashes back to Darwin's time on the Galapagos and to a water rumble between creationists in flashy Mexican wrestler costumes and evolutionists in scaly caps and lab coats.
"We're not being literal by any stretch of the imagination," says Sherri Chambers, who co-directs the production with Fluid Movement founder Keri Burneston.
The performance is typical Fluid Movement: a serious subject turned into a comedy through unconventional methods, particularly water ballet, says Burneston.
She and two other artists founded the group in 1998 to do community water ballets, though the group has done a belly dance show called 1001 Freudian Nights and used fire and flamenco dancing to act out Baltimore's Great Fire.
The group chose the evolution theme because it lends itself to water ballet, says Chambers.
It's impossible, Krandle says, to take the show too seriously.
Says Ted Alsedek, director of the Darwin-and-monkey scene: "We try to reflect both sides."
"And make fun of both sides," Beall chimes in.
The cast of about 70 includes not only Baltimore actors and performers, but also doctors, lawyers and teachers. Krandle guesses the average age is 35, with the youngest at 18 and the oldest in his 50s.
Organizers have little trouble finding dozens of amateur performers to wear bathing suits in public. Any self-consciousness, says Beall, is fleeting.
"You see that happening, [they] set that aside, and everybody struts," he says.
The group welcomes all swimming skill levels - last year, one performer was even fitted with flotation devices - and the first two weeks of rehearsal are usually spent teaching the basics of synchronized swimming, Chambers says. Planning began in February, but daily rehearsals started only in late June.
The show has several newcomers this year, including Rob Hatch, a freelance video producer who said he'd been waiting all year to be in the show.
"This is one of these art experiences where the whole is so much greater than the sum of its parts," Hatch says.
Though still dominated by women, the cast has almost 20 men, says Chambers.
"You put wrestling in a water ballet, and the guys show up," she says.