The tongue of the short-beaked echidna is the animal's only way of catching prey. It can stick out up to 180 mm outside the snout. The tongue is sticky because of the presence of glycoprotein-rich mucous. This mucus both lubricates movement in and out of the snout and helps to catch ants and termites, which stick to it. The protruded tongue is stiffened by the rapid flow of blood, allowing it to penetrate wood and soil. Retraction requires the contraction of two internal muscles. When the tongue is retracted, the prey is caught on backward-facing keratinous "teeth" along the roof of the buccal cavity. This allows the animal to both capture and grind food. The tongue moves with great speed, and has been measured to move in and out of the snout 100 times a minute.