A group of “mature” environmental activists in Florida took off their clothes for a fund-raising calendar that reflects their “ageless beauty.”

Fifteen models for the 2010 Women Sustaining the Earth calendar — ages 44 to 78 — posed in locations around the Florida Keys, according to The Miami Herald. So far, they’ve sold 500 calendars, raising $8,000 for the Green Living & Energy Education’s community garden.

Organizer Erika Biddle said she was inspired by the 2003 movie Calendar Girls, a true account of older British women who pose nude for a calendar to raise money for a friend with leukemia. Biddle’s Earth calendar was printed on chlorine-free, recycled paper and used soy inks.

Recalling California Gov. Arnold Schwarzenneger’s 2007 challenge for the environmental movement to become hip and sexy, Biddle began recruiting women 40 or older to celebrate Earth Day’s 40th anniversary in April.

“When I saw the movie, I thought, ‘Why don’t we do it?’” said Biddle, a 63-year-old radio show host. She began recruiting women who were ultimately photographed in various states of undress, some appearing totally naked and others covered with strategically placed strips of fabric or items of clothing. (The women decided just how “natural” they wanted to appear.)

Amy Culver, who posed under a waterfall wearing a white shirt, said when Biddle called she said, “Do you have the right number?”

“But then I thought about it,” said Culver, 44, who works on environmental issues. “So many young girls perceive the perfect size to be 0, 2 or 4. This is a golden opportunity to be celebrating natural beauty without facelifts and everything else.”

The calendar was photographed around Florida, with a steady supply of champagne on hand to calm the models’ nerves. Each month’s photo features a corresponding quote.

With the calendar sold out, Biddle says she is having more printed to meet the growing demand.

“It took a while to get used to the idea,” said Shirley Freeman, 74, a former mayor and commissioner of Monroe County. “This is a different side of me I really never have explored. And,” she said, “it’s for a good cause.”