Nav: Home

Australian lizard scares away predators with ultra-violet tongue

June 07, 2018

When attacked, bluetongue skinks open their mouth suddenly and as wide as possible to reveal their conspicuously coloured tongues. This surprise action serves as their last line of defence to save themselves from becoming prey says Martin Whiting, of Macquarie University in Australia, who conceived the study just published in Springer's journal Behavioral Ecology and Sociobiology. The research revealed that the back of the northern bluetongue skink's tongue is much more UV-intense and luminous than the front, and that this section is only revealed in the final stages of an imminent attack.

Bluetongued skinks of the genus Tiliqua are medium-large sized lizards widely found throughout Australia, eastern Indonesia and Papua New Guinea. They are well camouflaged but their strikingly blue tongues are distinct and are UV-reflective in species in which this has been measured. When attacked, they open their mouths wide to reveal their tongues.

The research team set out to investigate the tactics that bluetongue skinks use to ward off attackers, and focused on the largest of the bluetongue skinks, the northern bluetongue skink (Tiliqua scincoides intermedia). This omnivorous, ground-dwelling lizard of northern Australia is well camouflaged thanks to the broad brown bands across its back. However, birds, snakes, monitor lizards - all animals thought to have UV vision - are among its main predators.

First the researchers gathered information about the colour and intensity of different parts of the lizard's tongue using a portable spectrophotometer to measure the tongues of thirteen skinks. The first exciting finding was that the blue tongue is actually a UV-blue tongue. The researchers then established that the rear of the skinks' tongues was almost twice as bright as the tips. When a predator approached, the skinks would remain camouflaged until the very last moment, before opening their mouths widely and revealing their highly conspicuous UV-blue tongues.

The next part of the study involved simulating 'attacks' on these lizards using model (fake) predators. The team used a snake, a bird, a goanna (monitor lizard), a fox and a piece of wood as a control. The model predator attacks were simulated within a controlled environment.

"The lizards restrict the use of full-tongue displays to the final stages of a predation sequence when they are most at risk, and do so in concert with aggressive defensive behaviours that amplify the display, such as hissing or inflating their bodies", explains lead author Arnaud 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."

The more intense the attack and the risk they were experiencing, the more full-tongue displays the animals were seen to use, and the greater section of their tongues they would reveal. Such displays were also most often triggered by attacking birds and foxes, rather than by snakes or monitor lizards.

"The timing of their tongue display is crucial," adds 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."
-end-
Reference: Badiane, A. et al (2018). Why blue tongue? A potential UV-based deimatic display in a lizard, Behavioral Ecology and Sociobiology DOI: 10.1007/s00265-018-2512-8

Springer

Related Predators Articles:

To warn or to hide from predators?: New computer simulation provides answers
Some toxic animals are bright to warn predators from attacking them, and some hide the warning colors, showing them only at the very last moment when they are about to be attacked.
Dragonflies are efficient predators
A study led by the University of Turku, Finland, has found that small, fiercely predatory damselflies catch and eat hundreds of thousands of insects during a single summer -- in an area surrounding just a single pond.
Predators to spare
In 2014, a disease of epidemic proportions gripped the West Coast of the US.
Red-winged blackbird nestlings go silent when predators are near
If you're a predator that eats baby birds -- say, an American crow -- eavesdropping on the begging calls of nestlings can be an easy way to find your next meal.
A decade after the predators have gone, Galapagos Island finches are still being spooked
On some of the Galapagos Islands where human-introduced predators of Darwin's finches were eradicated over a decade ago, the finches are still acting as though they are in danger, according to research published today in the Journal of Animal Ecology.
Fear of predators causes PTSD-like changes in brains of wild animals
A new study by Western University demonstrates that the fear predators inspire can leave long-lasting traces in the neural circuitry of wild animals and induce enduringly fearful behaviour, comparable to effects seen in PTSD research.
Fear of predators increases risk of illness
Predators are not only a deadly threat to many animals, they also affect potential prey negatively simply by being nearby.
New study questions effects of reintroducing top predators
There's little evidence that reintroducing top predators to ecosystems will return them to the conditions that existed before they were wiped out, according to new research.
'Seeing' tails help sea snakes avoid predators
New research has revealed the fascinating adaptation of some Australian sea snakes that helps protect their vulnerable paddle-shaped tails from predators.
How water fleas detect predators
Water fleas of the genus Daphnia detect via chemical substances if their predators, namely Chaoborus larvae, are hunting in their vicinity.
More Predators News and Predators Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Climate Mindset
In the past few months, human beings have come together to fight a global threat. This hour, TED speakers explore how our response can be the catalyst to fight another global crisis: climate change. Guests include political strategist Tom Rivett-Carnac, diplomat Christiana Figueres, climate justice activist Xiye Bastida, and writer, illustrator, and artist Oliver Jeffers.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.