How Frogs and Toads Mate

The frog and toad calls that serve as a harbinger of springtime are actually mating calls. The ponds from which these amphibians call will soon be filled with developing tadpoles, evidence of the mating that occurred weeks before. But, if you have ever seen a frog or toad up close you will realize that it is nearly impossible to tell males from females because they have no external genitalia. Instead, both males and females have a single opening, called a cloaca, which is a common opening for the digestive, urinary and reproductive tracts. This begs the question, how do frogs and toads mate?

Generally speaking (there are exceptions), the mating process begins when males go to a body of water and begin to call. Many times there are several males calling from the same pond, which makes the calls sound even louder and more attractive to female frogs trying to find a pond in which to mate. Each frog species makes a unique type of call, but even within a species the sound of a frog's call can be different from one frog to the next. The frog calls you hear are very important in the process of frog and toad mating.

Like most other species of animals, female frogs carry eggs inside ovaries. Some species of frogs carry dozens of eggs while others carry thousands. These large egg-laden females make their way to the pond, lake, or stream (or even water-filled tire rut) attracted by the males calling from there and look for a mate. The female must be choosy, because she has many eggs that can only be fertilized by one male.

Once she has selected her mate, the female allows the male to climb on her back. She, by nature of the fact that she has to carry so many eggs, is larger than the male. He grasps her underneath her front arms and holds her tightly with his thumbs (which are large during the mating season) in what is known as amplexus. With the male on the female's back, their cloacae are lined up perfectly. Then, as the female begins to lay her eggs from her cloaca the male releases sperm from his cloaca and fertilizes them. This completes the mating process.

Depending on the species of frog or toad, the eggs can be laid in small clumps attached to vegetation (like leopard frogs), in long lines along the bottom (like toads), or in floating masses (like bullfrogs). Regardless of the configuration, these egg masses are allowed to sit in the water unattended to by either parent. Within a few days the embryos within the egg are developed enough to hatch from the egg and begin eating algae. These tadpoles will continue to eat, grow, and develop legs in the process of metamorphosis.