Swimming in northern terrestrial mammals

Abstract

Swimming mammals floated at a variety of angles correlated with hair and body fat present, and used a variety of gaits. In general small mammals with long tails used their hind legs alternately while large mammals and those with short tails paddled with four feet alternately as in the trot. The species that used their legs synchronously were either semiaquatic or had a phylogenetic background of hopping. During their development, mice and rats possessed six swimming gaits, including several asymmetrical gaits used by neonates, the early use of the front legs, the subsequent use of four legs, and the final use of hind legs, which was the adult gait. The developmental swimming patterns of guinea pigs, rabbits, hamsters, gerbils, and lemmings were less complex and concluded with the use of four legs, the adult gait. The ability to swim in a straight line was often a function of maturity, occurring sometimes before the eyes opened. The ability to hold the nose out of the water always preceded the opening of the eyes.