Primitive amphibians can be surprisingly handy.

professor caricatureProf. Mumblebard claims: “Frogs remain at a lower evolutionary level than lizards. Although certain frogs possess an opposable thumb, this is best explained as compensation for the fact that no frog possesses horny claws on its forelimbs.”

logoRobin and the Honey Badger respond: “Although there is no literature comparing dexterity in frogs and lizards, there is a categorical difference between these two groups which is unexplained by the presence or absence of claws. If dexterity is defined as differential deployment of the digits to prehend objects other than perches, no lizard shows dexterity but many lineages of frogs – including primitive ones – show dexterity. Prime examples are as follows.

  • Frogs in various arboreal, aquatic and terrestrial lineages have opposable digits, allowing them to use a precision grip to prehend prey manually and to place it in the mouth.
  • Certain aquatic frogs grasp prey detected by their fingertips in muddy water. Notably, African dwarf frogs are the only animals known to achieve dexterity with fully webbed hands.
  • Climbing frogs in at least two families hide their clutch by using the hind digits to wrap a leaf around sticky eggs deposited on the foliage.
  • Many or most frogs use their digits to rub off their skins during ecdysis, and certain perching frogs use their digits to spread sunscreen-like secretions over their bodies.
  • Various frogs beat albuminous secretions into foam nests, which may demand subtle movements of the digits rather than gross movements of the whole foot or hand.
  • Various frogs lure prey by differential gesturing with the hind digits. Not only do lizards fail to emulate such subtle movements of the feet, but no lizard is known to lure prey at all.
  • Male surinam toads and marsupial frogs use their hind digits to place the clutch on the back of the female, where the eggs hatch in special pouches. Female marsupial frogs use the tips of the hind digits to extract the offspring from the narrow opening of the pouch.
  • Male midwife toads stroke or probe the female cloaca with the tips of the hind digits during courtship. Although not particularly dexterous, this is remarkable in a lineage ancient enough to be called ‘living fossils’.

What deserves to be acknowledged for the first time is that frogs are the only vertebrates – with the partial exception of a few species of otters – which have evolved a combination of dexterity and clawlessness. The important implication of this is that frogs’ brains are, in certain respects, more advanced than those of lizards, despite the Amphibia being ancestral to the Reptilia.”


Please join us here at the Bio-edge with your own comments. In the discussion below we encourage links to any evidence supporting either Prof. Mumblebard or Robin and the Honey Badger. Illustrations are welcome but please cite all sources or we may be forced under copyright to delete your comment.