How Webbed Toes Help Frogs Swim

Not all frogs possess webbed feet, but most aquatic species feature well-developed webbing between their toes. The webbed feet are an adaptation that enables aquatic frogs to survive in their wet habitats.

  1. Aquatic Lifestyle

    • Lawrence E. Licht concretely demonstrated that the webbed feet of some frogs are inextricably linked to their lifestyle. The study, published in a 1986 issue of "American Midland Naturalist," compared the escape techniques of two closely related, sympatric species; the main difference between the two was that one of the species had webbing and one did not. Licht found that the species with webbed feet almost always jumped into the water to escape predators, while the species lacking webbed feet always escaped via the land. Much like flippers help to propel human scuba divers through the water, webbed feet increase the thrust and speed of swimming frogs. When the toes are extended and the webbing stretched taut, the frog has a much larger surface area to push against the water. When the frog retracts the leg, the webbing folds up, reducing the water̵7;s resistance. With webbed feet, frogs can swim quickly enough to evade predators and catch swift-moving prey like fish and crayfish.

    Identification Tools

    • Webbing characteristics help to identify some frog species. In the southeastern United States, bullfrogs (Rana [Lithobates] catesbeiana) and pig frogs (Rana [Lithobates] grylio) are sympatric and look very similar. The webbing of the bullfrogs̵7; feet is less extensive than that of the pig frog and doesn̵7;t reach the end of the longest toe like it does on the pig frog.

    Swimming Without Webbed Feet

    • While all frogs can swim, not all are specially equipped to do so. Tree frogs often lack webbing, as they rarely enter the water -- except they must do so for breeding and egg deposition. Frogs must use their limbs for things besides swimming: Tree frogs must hold onto perches; toads must manipulate large prey and males of most species must clasp females for amplexus. Because of this, webbed feet are not always advantageous; in fact, many frogs only have one set of webbed feet, allowing them some flexibility. When frogs display webbed and non-webbed feet, they usually have webbed rear feet and non-webbed front feet, but there are exceptions; Hallowell's tree frog (Hyla hallowellii) has extensively webbed front feet yet lacks webbing on the rear feet.

    Alternative Applications

    • Not all frogs with webbed feet are aquatic. Wallace̵7;s flying frog (Rhacophorus nigropalmatus) of Malaysia and Borneo has webbing on all four of its feet and uses them to glide from tree to tree. The frog has been observed gliding more than 50 feet from tree to tree. When landing, the frogs use their webbed feet to reduce the angle of approach and slow down to make a gentle landing. Scientists at the Biomimicry 3.8 Institute hypothesize that the webbed feet of aquatic frogs also function as parachutes when leaping, working to slow their descent.