Researchers studying the northern blue-tongued skink Tiliqua scincoides intermedia have found that its tongue is actually ultraviolet.
The main predators of this ground-dwelling Australian lizard include birds, snakes and monitor lizards, all of which are thought to have UV vision.
The researchers also established that the rear of the tongue is almost twice as luminescent as the tip and is only revealed in the final stages of an imminent attack.
“The timing of their tongue display is crucial,” explains lead author Arnaud Badiane. “If performed too early, a display may break the lizard’s camouflage and attract unwanted attention by predators and increase predation risk. If performed too late, it may not deter predators.”
The researchers later simulated attacks using mock predators. The number of full-tongue displays and the amount of tongue revealed directly correlated with the intensity of the attack and the threat of the predator.
Such displays were also most often triggered by birds and foxes, rather than snakes and monitor lizards.
“The lizards restrict the use of full-tongue displays to the final stages of a predation sequence when they are most at risk," adds Badiane. “This type of display might be particularly effective against aerial predators, for which an interrupted attack would not be easily resumed due to loss of inertia.”