Frogs and amphibians in general are our environmental “canary in a coal mine.” Because they have porous skin, and need to return eventually to water to avoid dessication, they absorb toxins from the environment into their bodies much quicker and to a greater extent than other animals do.
I set up a pond in my yard years ago to attract frogs, and boy does it. It’s turned into an anuran lovers’ lane.
Even with an amphibian-friendly yard, I still have only ever found three species of amphibian here: Cuban tree frogs, marine toads, and greenhouse frogs. Greenhouse frogs (eleutherodactylus planirostris) are the tiny little guys who could sleep on a dime with room to stretch out
They are not only adorable, but interesting in their own right, because contrary to everything you learned in grade school, the greenhouse frog forgoes the tadpole stage completely. Like a reptile, the frog lays her eggs terrestrially, in damp soil such as that found in potted plants (think “greenhouse”), or inside the “cup” of bromeliads, where plant matter and soil tend to accumulate. It really makes survival sense: aquatic frogs need to deposit a large amount of egg spawn in water, and hope a) it doesn’t dry out, and b) the water doesn’t contain too many predators like fish and insects. If your eggs are in or on moist soil or vegetation, they avoid these problems to some extent. Upon hatching, the frogs are fully formed versions of the adults, just smaller. Hatchlings can fit on your pinky nail with ease, and on close inspection have golden, almost metallic, patches on their sides.
While they don’t exist as tadpoles per se, greenhouse frogs do technically go through a tadpole stage, in ovum, where they can frolic and swim within the safety of an eggshell. It’s a great adaptation when you think about it, and one taken advantage of by reptiles.
Greenhouse frogs are native to the Caribbean, but are firmly established in South Florida. There are reports of them in the Florida Panhandle, as well as New Orleans. While they are non-native, I don’t believe they have created an invasive threat to native wildlife, though it’s true that the only three amphibians encountered in my yard all happen to be non-native.