The platypus is a semi-aquatic animal from Australia that appears to be assembled from several different creatures. Its existence challenges neat biological categorization and presents a unique combination of traits. With a form that is both strange and highly specialized, the platypus occupies a distinct niche in the animal kingdom.
Distinctive Physical Features
The most recognizable feature of the platypus is its bill, which, despite its duck-like shape, is not hard or bird-like. Instead, it is a soft, pliable, and rubbery structure covered in dark, leathery skin that functions as a sophisticated sensory organ. The animal’s body is streamlined and covered in dense, waterproof fur that provides excellent insulation by trapping a layer of air, keeping it warm in cold freshwater.
A platypus’s feet possess broad webbing that extends well beyond the claws, transforming them into powerful paddles for swimming. When the platypus moves onto land or needs to dig, this webbing can be retracted, exposing strong, sharp claws. These claws are used to excavate extensive burrows in the banks of rivers and streams where they live and raise their young.
The platypus’s tail is broad and flat, visually similar to a beaver’s. In the water, it acts as a rudder, helping the animal to steer as it propels itself with its front limbs. A significant function of the tail is fat storage, holding a large percentage of the platypus’s total body fat reserves. This stored energy provides sustenance when food is scarce or during egg incubation.
An Egg-Laying Mammal
The platypus belongs to an exclusive group of mammals known as monotremes, distinguished by their ability to lay eggs. This reproductive strategy is rare among mammals, shared only with the echidnas of Australia and New Guinea. The female platypus typically lays between one and three small, leathery-shelled eggs in a nesting chamber deep within her burrow. She incubates them by curling her body around them, providing warmth and protection until they hatch after about 10 days.
After hatching, the young, called puggles, are dependent on their mother for nutrition. Platypuses exhibit a unique form of lactation, as females do not have nipples. Instead, milk is secreted from pores in the skin of her abdomen. This milk collects in grooves on her belly, allowing the puggles to lap it up directly from her fur. The young will nurse for three to four months before they are developed enough to leave the burrow and begin foraging on their own.
The Male’s Venomous Spur
A unique defensive and competitive feature is found only on the male platypus. Located on the hind ankle is a sharp, hollow spur connected to a venom gland in the upper leg. This makes the platypus one of the very few venomous mammals in the world. The production of venom increases significantly during the breeding season, indicating its primary use.
The venom is not used for hunting prey but is instead employed by males during territorial disputes and for dominance when competing for mates. While the venom can be lethal to smaller animals, such as dogs, its effect on humans is not deadly but is known to be intensely painful. A sting from a platypus spur causes immediate and severe pain, followed by rapid swelling that can spread through the affected limb. The resulting hypersensitivity to pain may persist for weeks or even months.
Extraordinary Sensory Perception
When a platypus dives, it hunts with its eyes, ears, and nostrils sealed shut. The soft bill is covered with thousands of specialized receptors. It uses electroreception to detect the minute electrical fields generated by the muscle contractions of its invertebrate prey, such as shrimp, worms, and insect larvae hiding on the riverbed. This allows the platypus to locate food with precision in murky water without relying on sight.
Adding to its unusual biology is a recently discovered characteristic of its fur. Under ultraviolet light, platypus fur exhibits biofluorescence, glowing with a bluish-green color. The specific reason or evolutionary advantage for this trait remains unknown to scientists, making it another puzzling aspect of this animal.