<P> Frogs range in size from the recently discovered 7.7 - millimetre (0.30 in) Paedophryne amauensis of Papua New Guinea to the 30 - centimetre (12 in) goliath frog (Conraua goliath) of Cameroon . The skin hangs loosely on the body because of the lack of loose connective tissue . Frogs have three eyelid membranes: one is transparent to protect the eyes underwater, and two vary from translucent to opaque . They have a tympanum on each side of their heads which is involved in hearing and, in some species, is covered by skin . True toads completely lack teeth, but most frogs have them, specifically pedicellate teeth in which the crown is separated from the root by fibrous tissue . These are on the edge of the upper jaw and vomerine teeth are also on the roof of their mouths . No teeth are in the lower jaw and frogs usually swallow their food whole . The teeth are mainly used to grip the prey and keep it in place till swallowed, a process assisted by retracting the eyes into the head . The African bullfrog (Pyxicephalus), which preys on relatively large animals such as mice and other frogs, has cone shaped bony projections called odontoid processes at the front of the lower jaw which function like teeth . </P> <P> The structure of the feet and legs varies greatly among frog species, depending in part on whether they live primarily on the ground, in water, in trees or in burrows . Frogs must be able to move quickly through their environment to catch prey and escape predators, and numerous adaptations help them to do so . Most frogs are either proficient at jumping or are descended from ancestors that were, with much of the musculoskeletal morphology modified for this purpose . The tibia, fibula, and tarsals have been fused into a single, strong bone, as have the radius and ulna in the fore limbs (which must absorb the impact on landing). The metatarsals have become elongated to add to the leg length and allow the frog to push against the ground for a longer period on take - off . The illium has elongated and formed a mobile joint with the sacrum which, in specialist jumpers such as ranids and hylids, functions as an additional limb joint to further power the leaps . The tail vertebrae have fused into a urostyle which is retracted inside the pelvis . This enables the force to be transferred from the legs to the body during a leap . </P> <P> The muscular system has been similarly modified . The hind limbs of ancestral frogs presumably contained pairs of muscles which would act in opposition (one muscle to flex the knee, a different muscle to extend it), as is seen in most other limbed animals . However, in modern frogs, almost all muscles have been modified to contribute to the action of jumping, with only a few small muscles remaining to bring the limb back to the starting position and maintain posture . The muscles have also been greatly enlarged, with the main leg muscles accounting for over 17% of the total mass of the frog . </P> <P> Many frogs have webbed feet and the degree of webbing is directly proportional to the amount of time the species spends in the water . The completely aquatic African dwarf frog (Hymenochirus sp .) has fully webbed toes, whereas those of White's tree frog (Litoria caerulea), an arboreal species, are only a quarter or half webbed . </P>

Where does the frog have the most muscle