Feeding ecology and diet

The platypus is a predator, mainly feeding on bottom-dwelling aquatic insects such as caddis-fly and mayfly larvae. The platypus is also partial to worms, snails, freshwater shrimps and crayfish, and pea-shell mussels. The size of its prey is limited by the fact that platypus teeth are lost quite early in development and replaced by flat, molar-like grinding pads at the back of the mouth. Unlike most mammalian teeth, these pads grow constantly to compensate for surface wear.

A platypus may find food by digging under banks or snapping up morsels floating on the water surface, as well as searching along the bottom sediments. Small prey is stored temporarily in cheek pouches while an animal is submerged. A foraging platypus typically remains underwater for 10-60

A duck-billed platypus (Ornithorhynchus anatinus) swimming underwater in Tasmania. (Photo by Erwin & Peggy Bauer. Bruce Coleman, Inc. Reproduced by permission.)

seconds before returning to the surface to breathe and chew its meal with a side-to-side motion of the jaws.

Its eyes and ears are located within shallow, muscular grooves on the sides of the head that automatically pinch shut when an animal dives. The platypus mainly relies on its bill to find food underwater. The surface of this remarkable organ is densely packed with tens of thousands of specialized sensory receptors, sensitive to either touch and vibration (push rods) or electrical currents (mucous sensory glands). It has been shown experimentally that the platypus is capable of registering the tiny amount of electricity generated in the water by the tail flick of a shrimp at a distance of around 2 in (5

A duck-billed platypus (Ornithorhynchus anatinus) walking in the grass in Australia. Usually platypuses are active after dusk and before dawn. (Photo by J & D Bartlett. Bruce Coleman, Inc. Reproduced by permission.)

cm). In turn, this information presumably is used to detect as well as track down the location of prey.

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