The platypus' flat tail, duck-bill, short legs, and webbed feet are all characteristics enabling it to hunt in aquatic environments. However, since it spends most of its time on land, it has a few physical traits that can be modified depending on its particular location. For instance, on its webbed feet, the five individual digits end in claws. When the platypus is in the water, the skin of its webbed forefeet extends beyond these claws, so that it can better use its forefeet to paddle. On land, however, this skin folds back, revealing the claws, thus enabling the animal to dig.
The platypus' eyes and ears have similar modifications. Both are surrounded by deep folds of skin. Underwater, the platypus can use this skin to close its eyes and ears tightly; on land, it is able to see and hear quite well. Interestingly, the platypus' nostrils, which are located at the end of its bill, can only function when its head is above water as well. Thus, when the platypus is submerged with its eyes and ears covered and its nose inoperable it relies heavily on its sense of touch. Fortunately for the platypus, its leathery bill is very sensitive and, therefore, is its primary tool in locating prey while underwater.
Like all male members in the order Monotremata, the male platypus has spurs on each ankle connected to poison glands in its thighs. Rather than using these poisonous spurs to attack prey, the platypus only uses them against other platypus or predators.