It’s increasingly common for artists to take up the cause of endangered species, and for good reason. But perhaps not many use the medium of ceramics. In an exhibition titled “the animals are innocent” at Middlebury’s Henry Sheldon Museum of Vermont History, Maryland artist, author and environmentalist Dana Simson presents ceramic boats as well as paintings featuring animals and a message. Unlike grim images of starving polar bears and plastic-entangled turtles, however, Simson’s works are gaily colorful and kind of adorable. But if her folk-art style is beguiling, her goal is serious: to show that animals are losing habitat and food resources, and suffering as a result of pollution and climate change.