The platypus stands as one of nature’s most peculiar animals, a mammal that lays eggs and possesses a distinctive duck-like bill. Its unique combination of traits often leads to questions about its anatomy and how it manages to feed. A common query revolves around its mouth: does this strange creature have teeth?
The Fleeting Teeth of a Juvenile Platypus
Platypuses are born with teeth, though these are not permanent structures like those found in most mammals. A young platypus, or hatchling, develops a small set of molars, typically one premolar and two molars on each side of the upper jaw, and two to three molars on each side of the lower jaw.
These teeth are vestigial and serve a temporary purpose. They are either shed or worn down to the gums by the time the juvenile platypus is weaned and ready to leave its natal burrow. This prepares the mouth for the adult feeding mechanism.
The Adult Platypus Grinding Mechanism
As platypuses mature, the lost teeth are replaced by tough, keratinous grinding pads. Keratin is the same strong protein found in human hair and fingernails, as well as the claws, horns, and hooves of other animals. These durable pads are located at the back of the platypus’s jaws and grow continuously to counteract wear.
An adult platypus uses its sensitive bill to scoop up bottom-dwelling invertebrates, such as insect larvae, freshwater shrimps, and worms, along with a mixture of gravel and sand from the riverbed. This collected material is then stored in cheek pouches while the platypus remains submerged. Upon surfacing, the platypus uses its robust grinding pads to mash the food and the exoskeletons of its prey against the ingested grit, processing its meal.
Evolutionary Clues in Fossilized Teeth
The fossil record offers evidence of the evolutionary journey of platypus dental structures. Ancient platypus ancestors, like the genus Obdurodon, possessed fully functional teeth that were retained into adulthood. For instance, Obdurodon dicksoni had a spoon-shaped bill and well-developed, rooted teeth, suggesting a more varied diet including larger prey like fish or frogs.
Another species, Obdurodon tharalkooschild, was a larger, carnivorous platypus with robust teeth, fed on crayfish, other crustaceans, and even small vertebrates such as lungfish and turtles. The evolutionary shift towards losing permanent teeth in modern platypuses is an adaptation to a diet of soft-bodied invertebrates mixed with abrasive grit. This change may have been driven by competition for hard-bodied prey from other species, like the Australian water rat, leading to specialization in softer food sources. The development of electroreceptive organs in the bill, with enlarged nerves occupying space where tooth roots once were, might also have contributed to this unique dental evolution.