Webbed feet are prevalent in frogs, but they're definitely not a universal feature -- though all frogs are amphibians. Frogs who reside in aquatic environments possess webbed feet, and those who primarily inhabit terra firma are free of them.
Identifying Webbed Feet
Identifying webbed feet in frogs is pretty straightforward. Frogs are equipped with four legs. The feet on the two in the front have only four toes, while the feet of the back legs instead possess five of them. Not only do the back feet have more toes, they're also often webbed, unlike those in the front. If a frog has webbed feet, you'll note the conspicuous presence of flaps of skin situated in the middle of the toes.
Webbed feet assist them in swimming. Frogs who have them swim faster. They create more surface area, allowing the frogs to apply more force against the surrounding water. More surface area equates to more power. The strength of the leg muscles also come into play, but a frog with stronger legs but no webbing would not be able to propel himself as fast as a frog with weaker legs but webbing between the toes of the rear feet. As the frog strikes backward with his leg, the webbed foot opens, creating a dam against the water. When the frog pulls the leg back to his body, the webbing closes, streamlining the foot's movement through the water back to position.
Leaping and Webbed Feet
Webbed toes can also sometimes help them with leaping; they're extremely useful for quickly getting away from predators. Some frogs with webbed feet are able to jump over impressive ground -- think roughly 20 times lengthier than their own physiques. Flying frogs from the genus Rhacophorus are particularly noteworthy in the jumping department, as their names hint. These Asian frogs have additional webbing on their feet. When they stretch their feet out, they basically employ them as handy parachutes, minimizing the speed at which they descend.
Webbed toes aren't the only exciting foot adaptation in the frog universe. Tree frogs, for instance, make up for what they lack in webbing by sporting convenient circular sticky pads on their feet instead. These pads are situated on their toes' tips, and adhere the frogs via suction to everything from damp foliage to branches and trunks. This makes going up and down trees a significantly easier process for tree frogs.
- Exploratorium: The Amazing, Adaptable Frog
- Ask Nature: Feet Used for Powerful Swimming - True Frogs
- Frogs - Awesome Amphibians; Sally Murphy
- Frogs - The Animal Answer Guide; Mike Dorcas and Whit Gibbons
- Northern Territory Government Department of Arts and Museums: Frogs Alive!
- Frogs and Other Amphibians; Bobbie Kalman
- Frogs; Kevin J. Holmes
- Animal Planet: Frog
- US National Library of Medicine National Institutes of Health: Propulsive Force Calculations in Swimming Frogs