The echidna, also called the spiny anteater, is one of the world’s most unusual mammals. Along with the platypus, it belongs to the order Monotremata, the only group of mammals that lay eggs. This unique evolutionary lineage has resulted in a creature with highly specialized anatomy, particularly concerning its feeding habits. Examining the structure of its mouth reveals how this animal successfully forages and consumes its prey despite major limitations.
The Unique Monotreme Mouth
Echidnas do not possess the traditional teeth found in nearly all other mammals, a trait they share with the platypus. Instead of a wide mouth designed for chewing, the echidna has a long, slender, beak-like snout, known as the rostrum. The mouth opening is remarkably small, located at the very tip of the snout and measuring only about 5 millimeters wide in the short-beaked species.
The jaw muscles of the echidna are not built for the powerful up-and-down crushing action associated with chewing. Their mandibles are connected by ligaments that prevent the orthal hinge movements common in other mammals. This arrangement means their jaw movement is primarily a rotation around the long axis of the lower jaw. This specialized mechanism facilitates a rapid, snapping or sucking motion used to ingest prey.
Processing Food Without Dentition
The echidna relies on an entirely different mechanism to process its food for digestion. This process is centered on the animal’s long, protrusible tongue, which can extend up to 180 millimeters outside the snout. The tongue is covered in a highly viscous, sticky mucus, composed mainly of glycoprotein, which allows it to capture numerous ants and termites rapidly.
Once the prey is pulled into the buccal cavity, mechanical breakdown begins. The echidna achieves the necessary grinding action by crushing the insects between two specialized, hardened surfaces. The first surface is a series of keratinous spines or ridges located near the base of the tongue. These spines work in opposition to the second surface: keratinous pads or ridges on the hard palate, the roof of the mouth.
The unique rotating jaw mechanism allows this capture and grinding to occur almost simultaneously, effectively pulverizing the prey against the hard palate. This process is crucial because, unlike most other mammals, the echidna and platypus have lost the genes for a conventional stomach and strong stomach acid. The mechanical grinding in the mouth compensates for the lack of strong chemical digestion later in the gut.
Specialized Diet
The echidna’s anatomy is perfectly suited to its diet, which consists almost entirely of soft-bodied invertebrates. This feeding behavior is known as myrmecophagy, meaning the consumption of ants and termites. The soft nature of this prey means the animal does not require the shear strength of teeth.
While termites and ants are the staples, echidnas also consume other small invertebrates like insect larvae and earthworms, depending on the species and geographical location. The insects’ hard exoskeletons are thoroughly crushed by the keratinous grinding pads before they are swallowed. The reliance on this diet means the echidna’s foraging strategy involves using its sharp claws to tear open logs and termite mounds, followed by the rapid, sticky tongue action to harvest the exposed prey.