Membranes of skin between fingers and toes of animals
Interdigital webbing refers to the presence of skin membranes. Normally, in mammals, webbing is present but resorbed later in development, but in various mammal species, it occasionally persists in adulthood.[1] In humans, it can be found in those suffering from LEOPARD syndrome and from Aarskog–Scott syndrome.[2]
Interdigital webbing is not to be confused with syndactyly, which is a fusing of digits and occurs rarely in humans. Syndactyly specifically affecting feet occurs in birds (such as ducks), amphibians (such as frogs), and mammals (such as the kangaroo).
Among shrews, the members of the genera Chimarrogale of southeastern Asia and Neomys of western Eurasia have interdigital webbing, as does the American water shrew (Sorex palustris) of North America, but it is more well-developed in Nectogale elegans of montane Asia. Webbing is also present in the Pyrenean desman (Galemys pyrenaicus).[3]
All otters have interdigital webbing, in the fore or hind limbs or both, to aid in aquatic propulsion. In sea otters, the webbing is covered with hair, at a density of 3300 hairs per square centimeter.[15]
Whales
Pits present on the sides of fossil proximal phalanges of pakicetids, ancestral whales, suggest that these animals had interdigital webbing,[16] a development hypothesized to lead to the fluke,[17] spurred by FGF8, a fibroblast growth factor.[18]
Braun, J.K. and Díaz, M.M. 1999. Key to the native mammals of Catamarca Province, Argentina. Occasional papers of the Oklahoma Museum of Natural History 4:1–16.
Cooper, L.N., and J.G.M. Thewissen. 2009 The role of FGF-8 in the origin of interdigital webbing in cetaceans. Presentation, Society of Integrative and Comparative Biology, Boston, Massachusetts.
Harding, Larisa E.; Smith, Felisa A. (2009). "Mustela or Vison? Evidence for the taxonomic status of the American mink and a distinct biogeographic radiation of American weasels". Molecular Phylogenetics and Evolution. 52 (3): 632–42. doi:10.1016/j.ympev.2009.05.036. PMID19501660.
Kerbis Peterhans, J.C.; Patterson, B.D. (1995). "The Ethiopian water mouse Nilopegamys Osgood, with comments on the evolution of semi-aquatic adaptations in African Muridae". Zoological Journal of the Linnean Society. 113 (3): 329–349. doi:10.1111/j.1096-3642.1995.tb00937.x.