Many animals have curious adaptations that give them an advantage in surviving the sometimes-rugged natural world in which they inhabit. One such amphibian that exhibits this type of adaptation is one that is common right here in Texas, the Couch’s Spadefoot.
Couch’s Spadefoots ( Scaphiopus couchii) belong to a frog family that has four representatives here in Texas. This particular variety occurs throughout most of the western two-thirds of this state, occupying grasslands and mesquite scrublands. It also occurs less frequently in the creosote flats of the driest portions of the Trans-Pecos. It occasionally can be seen living around cultivated fields and gardens. Outside of Texas it can be observed from western Oklahoma westward to southern California and then southward to central Mexico.
This species can be quite variable in appearance. The ground color can vary from different shades of brown and tan to olivegreen to almost lime green. Along the back are broad reticulated lines that form busy random patterns. These lines can vary in color from yellow, lime, or olive. The sides are not as colorful as the dorsal pattern fades into a light creamy colored belly. Adult females are the larger sex, with mature individuals approaching almost three inches. Males are smaller, seldom exceeding two inches.
This variety of spadefoot is the largest and by far the most colorful species of the genus.
While being toadlike in appearance, there are three characteristics that separate spadefoots from true toads. Unlike true toads, spadefoots’ pupils are elliptical, and the skin is smooth and lacks warts. Spadefoots also have a single elongated crescent-shaped sickle on each heel that is utilized for digging deep into the ground.
This sickle is where the namesake of spadefoot originated from.
The behavior of this amphibian is dependant primarily upon surface moisture.
While small rainstorms may cause other amphibians to come out of hiding, it takes substantial rain amounts to lure this species out from the depths of the earth. In fact, this species has been known to remain underground for several YEARS awaiting adequate rainfall to reproduce. It utilizes the sharp spade on its hind legs to dig a deep burrow where it encases itself in a thin membrane-shell made from skin secretions. It is here where the metabolism of the spadefoot slows to the point where it can remain for vast amounts of time in a state of “hibernation”, waiting for the ample rainfall amounts it needs to reproduce.
Research has shown that low-frequency sounds from falling rain is what draws this species to the surface.
Like other amphibians, Couch’s Spadefoots live a dual life. When the rains have fallen enough for them to emerge from their earthly bed, adults will congregate at shallow pools where males will call for the attention of females. Once a receptive female approaches, the male will clasp the female around the waist and externally fertilize up to three thousand eggs.
This activity is known as amplexus. Once the eggs hatch, the fishlike tadpoles are primarily carnivorous, and as the pools dry up, the tadpoles begin to compete for food to the point of cannibalism.
Over the period of just days, the tadpoles metamorph into small froglets, developing air-breathing lungs rather than gills, absorbing the tail, and developing legs.
Spadefoots are unique creatures, and many times are mis-appropriately called spadefoot toads. Their skin secretions are toxic, although not enough to harm humans, and smell remarkably like vinegar.
There are cases of humans having an allergic reaction, however, so always wash your hands if you choose to touch this intriguing little amphibian.
