Happy Saint Patrick’s Day! We thought today could be a fun time to discuss some of our under-appreciated native animals: green anoles, rough and smooth green snakes, and green tree frogs. All of these little guys are critical parts of our ecosystem because they help control pest populations. Unfortunately, they’re all also experiencing population declines due to pesticides, habitat loss, and capture for the pet trade.
You might have noticed that green is a relatively rare color in wildlife. Green birds are rare, green reptiles and amphibians are fairly uncommon, and green mammals don’t even exist! That’s because animals are incapable of producing green pigment. Animals can appear green for one of two reasons (or occasionally, a combination of the two)— some, like certain corals, produce green pigment with the help of algaes and other plants. The majority of green animals, though, are green due to structural coloration.
Our local green lizards, snakes, and frogs fall into that category. Structural coloration happens when the microscopic texture of the animal’s skin, feathers, or scales causes it to reflect a specific part of the spectrum of light. If you were to look at these animals’ bodies under an electron microscope, you’d just see interlinking chains of gray, brown, cream, yellow, black, or white, but the underlying crystal-like structure appears green when we look at the animal without the aid of a microscope.
Some animals, like our native green anoles, can even use specialized cells called chromatophores to alter the position of the cells controlling yellow and brown pigment, so as to block light from reflecting on their structurally green scales. This ability to change color is what earned them the nickname “American chameleon.”
What’s your favorite green animal?