New series. Zoo keepers are concerned about pregnant elephant Thi as they believe she may be three months overdue. The risks for Thi and her unborn calf are growing by the day, and the keepers are worried. Meanwhile, rampant male Rothschild giraffe Meru causes problems for the giraffe herd as he relentlessly chases the females, and male clownfish Polo gets injured while fighting with the other males for the attentions of dominant female Rosie. However, clownfish can change sex at will, and Polo's time alone in an isolation tank produces a surprising side effect.