Florida's big-league baseball team, the Marlins, take their name from a fish blessed with athleticism and elegance. The same cannot be said for their new cheerleading troupe.

The Manatees, who made their debut at the Marlins' opening game of the season in Miami on Monday night, share their name - and agility level - with a marine mammal known for its blubber, laid-back speed and unfortunate tendency to get tangled in boat propellers.

Ranging in weight from 16st to 30st (101kg to 190kg), the Manatees are baseball's first all-male, plus-size cheerleading squad. In contrast to the Memaids, the Marlins' trim female cheerleaders, the Manatees' eye-popping vital statistics give new meaning to the phrase “ball-park figures” and have inspired nicknames such as Bulldozer, Tank and Mr Mantastic.

Routines consist of plods, struts, wiggles and grooves, belly-jiggling, buttock-slapping and hungry expressions, set to songs that include the rap hit Peanut Butter Jelly Time and Michael Jackson's Don't Stop 'Til You Get Enough.

“Stay down as low as you can go,” the choreographer Vanessa Martinez-Huff, 28, instructed the Manatees as she led them through some squats at final rehearsals. “Without hurting yourselves,” she added anxiously, as the room trembled with pained grunts.

The Manatees include a 61-year-old, 23st pastor, who is doing it to convince youths at his church that anything is possible, and a 24-year-old, 30st security guard (nickname: Tiny), who dreams of becoming a professional dancer.

Baseball fans are urged to laugh with the Manatees, not at them. Steve Bauer, 33, a 20st peanut vendor, admits that walking up the stairs to rehearsals is more exercise than he is used to, and says: “If I cared what people think, I'd be skinny.”