Temperatures rise as the zoo is hit by a heatwave. Many of the animals are well adapted to the sun, but those from cooler climates need extra attention. The boys devise a series of ingenious tricks to keep each animal cool, including ice baths, mist showers and giant ice lollies. It’s fish flavour for the penguins, lettuce lollies for Marion the tortoise and a huge blood lolly for the big cats.