Bluff- and baffle-displays in lizards, part 3
(writing in progress)
Genera of lizards with peculiarly Australian specialisations for anti-predator bluff include species not showing the syndrome:
I’ve been describing the peculiarly Australian syndrome of morphologically specialised, anti-predator bluff in lizards. In this Post, I’d like to make a simple point that I’ve never seen made in the literature although it should be obvious: that several of the genera involved include species that show this syndrome, and other species that do not show it. This proves that the syndrome is phylogenetically plastic.
In the genus Tiliqua of the skink family, there are 8 species in Australia and the nearby islands of Indonesia. All of these have a morphologically specialised bluish tongue, which is not sexually dimorphic and cannot possibly be explained by foraging. It is specialised for anti-predator display and this display is certainly false = a bluff because the lizards have no particular defence although like any lizard they can bite. There is nothing particularly intimidating about their bite apart from the obvious: these are among the largest skinks and also have proportionately large heads. In the west we have Tiliqua occipitalis, in the east we have T. scincoides, in New Guinea we have T. gigas, and in the southeast we have T. nigrolutea; all four of these species are similar in opening the mouth wide and sticking a broad bluish tongue far out in a lurid anti-predator display that, as far as I know, has no intraspecific application. The latter point has not been made in the literature as far as I know, even though it is tacitly acknowledged by everyone. In central Australia we have T. multifasciata, and this species has the same specialised tongue but, based on the photos I’ve seen so far, seems to display it by sticking it far out without opening the mouth wide. Perhaps this is to save water in its arid habitat? The final species with this kind of tongue is T. rugosa, which differs from its congeners in having more robust protective scales on its body, and in having extreme reproduction with monogamy, precociality, and parental care, and is widespread across the mesic and semi-arid parts of southern Australia. But the important species to consider in this genus is the small, geographically restricted (formerly believed extinct) T. adelaidensis, which seems to lack a broad, specialised tongue. This small rare species does open its mouth to display, but there seems to be nothing special about the mouth: all that is shown is the flesh-coloured interior, with no blue tongue evident and no tongue stuck out. So the smallest member of this genus does not seem to conform to the display and lacks the morphological specialisation of the tongue.
A similar picture can be drawn in the family Agamidae, for the genus Pogona.
Re the peculiarly Australian syndrome of morphologically specialised bluff in lizards: need for a new term
Perhaps I could explain further my translating into human terms.
Imagine you’re travelling through a really crime-ridden part of town, and you have to deploy tactics when thugs spot you as a mug. You have no weapon. You have three broad options.
Firstly, you could carry a wooden pistol, and pull it out when approached by thugs. This is analogous to false aposematism = Batesian mimicry. You risk your life because the thugs might twig to the fact that the gun is false. But it could buy you time and sometimes it’ll work. This is not what Tiliqua and Chlamydosaurus do, because they neither have a hidden weapon nor do they pretend to have a hidden weapon. The last point is so original and so important that I’ll repeat it: these lizards are not pretending to have a hidden weapon, because ‘my tongue is dangerous’ or ‘my neck-frill is dangerous’ are simply not credible claims; no animal has such things.
Your second possible tactic is: when you are spotted by thugs, go all spastic and pretend to be really mad, shouting, singing, becoming uncoordinated, pissing or shitting, taking your clothes off, i.e. really odd, confusing behaviour. The thugs will no doubt suspect your tactic but it takes them time to think about it and that time can mean life or death. The important point about this kind of BULLSHIT BLUFF is that it’s MERELY BEHAVIOURAL, so you’re not committed to it. If you think it won’t work, you just don’t do it, because no STRUCTURE (apart from expendable clothes, possibly) OR ORGAN in your body is needed for it. I can well imagine myself using such tactics, which make sense because they trade on psychology but don’t impose FIXED COSTS AND LIMITED OPTIONS.
Thirdly, you can do what our Australian lizards do: you can walk around, for example, in huge iron shoes, or strap pterodactyl wings to your back with secure knots, or tattoo your whole body permanently with luminous yellow just as a precaution for forays such as this. Now, once again the bullshit might baffle your thugs, but the problem is that a) you’ll pay heavily for the tactic even if you don’t meet any thugs at all, because there’s a structural compromise and commitment involved, and b) if your ploy fails, you’re stuffed: you’ll keep paying for the burden you’ve locked into, but you’ll get no payoff and, worse, you could actually attract predation from smart thugs who’ve figured out that you’re a bullshit artist.
Re the peculiarly Australian syndrome of morphologically specialised bluff in lizards: need for a new term:
A good example of a biological pattern/phenomenon ‘hiding in plain sight’ is the fact that it’s mainly in Australia that lizards have evolved organs/physical structures in their bodies which function mainly in bluffing would-be predators. Even after one brings this pattern into focus, it’s hard to explain its significance without coining a new term for it. People find it hard to appreciate any abstract concept that lacks a name.
There are two organs which we could use as examples, the wide blue tongue of most species of Tiliqua and the frill of the frill-necked lizard Chlamydosaurus. What’s been missed by everybody, despite the fact that both of these animals are familiar to most Australians, and extremely familiar to any Australian faintly interested in biology, is that such structures are rare in organisms beyond these lizards and beyond Australia. It’s easy to accept that the lizards are bluffing predators, but the more one thinks about this the more interesting it becomes.
I’d like to make two points about these tongues and this neck-frill. On that basis I’d like to suggest a new term that does justice to their categorical difference from other organs/structures.
Firstly:
Both the broad, blue tongues of Tiliqua and the neck-frill of Chlamydosaurus evolved mainly for display against would-be predators. These structures are NOT likely to be useful for any other purpose, such as eating or thermoregulation or social communication, because if they were then one would expect similar structures to have evolved on other continents too – and they have not. What this means is that these structures are SPECIALISED for ANTI-PREDATOR DISPLAY, which is significant because this presumably involves a COST to the lizards.
Secondly:
The interesting thing about these structures is that they convey no useful information to the predator. Instead of being informative in the way the aposematic structures or features of other animals (e.g. the hood of various species of cobras) are, they are, in a sense,’anti-informative because they waste the time and cognition of the would-be predator with NONSENSE. There is no way a broad blue tongue can per se be dangerous, for there are no animals out there, anywhere, which have toxic tongues. This leaves the would-be predator bewildered/befuddled/confused/mystified, as opposed to being informed about a real hidden weason. Tiliqua and Chlamydosaurus have no hidden weapon; nor are they mimicking animals that do have a real hidden weapon, which is a form of deception and bluff but different in being INFORMATIVE.
It’s one thing to lie about one’s weaponry, in the way Batesian mimics lie; the information is false but the information is specific. I.e. Batesian mimics provide clear information but that information is false. What’s happening with our Tiliqua and Chlamydosaurus is that they are not only failing to provide information, they are delaying or preventing communication to the would-be predator, by throwing up what I think is best called a BAFFLE.
The broad, blue, protrusible tongue of Tiliqua is what I would suggest we call a ‘baffle-organ’ because it is anti-informative. Not only is the would-be predator none the wiser for being shown these organs/structures, but its time and attention and cognition have been WASTED by these organs.
The terms ‘distraction’ and ‘confusion’ don’t fit the bill for me, because a better example of distraction is the bright blue of a skink’s tail, which draws the attention of the predator to the wrong, less vulnerable pole of the body and facilitates tail-autotomy as a means of escape. ‘Confusion’ is just too vague. Yes, it’s true that the broad, blue, protrusible tongue of Tiliqua and the neck-frill of Chlamydosaurus are CONFUSING to a would-be predator, but there are so many ways in which a lizard could confuse its predators that it would not be appropriate to hijack this word to the confines of a restricted meaning. ‘Baffle’ is to my mind a suitable word to co-opt because it’s not commonly used and its meaning is apt, so it deserves a new status as a label for this particular tactic. People will no doubt appreciate the tactic more easily once it is endowed with a name, not so?
Some readers may think, at this point, that I’m making too much of something that is not that big of a deal. I would argue that these structures/organs are quite a big deal, because they are categorically different from other organs used against potential predators. The thing is, when Tiliqua evolved a baffle-organ in the form of this particular type of tongue, it because specialised in a way that is inevitably costly in one way or another. A similar argument can be applied to the neck-frill of Chlamydosaurus, which is undoubtedly an encumberance in various ways (and again, if someone argues ‘no it isn’t’ then I’ll just ask them ‘why is it, then, that similar structures/organs have not evolved more widely in lizards, including other continents?).
But the following really is the ‘kicker’ in all of this, the concept that justifies the endowment of a new term to this tactic and its structures/organs. Once one has specialised morphologically, in the sense that every adult Tiliqua or Chlamydosaurus grows its special tongue/special neck-frill whether it likes it or not, and has to pay for it regardless, then that amounts to a dependence on that structure/organ paying for itself. And that payoff is conceptually fascinating, because it is so easy to imagine, on a continent such as Africa, that the commitment and specialisation could fail dismally. All that a smart predator, encountering a Tiliqua, would have to realise is that ‘this broad, blue, protrusible tongue is a complete lie’, and the game is up; the predator will simply kill the lizard every time after that, and the whole evolutionary investment becomes a liability.
That’s what’s really spectacular about these structures/organs: their specialisation signifies a COMMITMENT to the deployment of NONSENSE, and a DEPENDENCE on most potential predators being baffled every time there is an encounter between the lizard and a potential predator. I think that’s a really interesting biological concept. Can you think of any other animal, anywhere on Earth, that has a baffle-organ along the lines that I’ve described here?
I can only imagine that the only situations in which animals would evolve baffle-organs (= organs specialised to LIE MEANINGLESSLY about a prey animal’s defensive capability) are those combining a) relative infrequency of predation, i.e. sparse populations of predators, and b) relative stupidity of predators, e.g. marsupials instead of eutherians, or reptiles instead of birds. And such a place, indeed, is Australia owing to its combination of limited area, drought, and infertility. This is obvious when one observes the tameness of a large lizard such as the eastern water dragon, Physignathus leseurii, which approaches human campers and steals their sandwiches in New South Wales canyons (in the wild Blue Mountains just west of Sydney) much as would some animal out on an oceanic island where there are hardly any predators. Semi-tameness is widespread among Australian animals and this is evidence for the relatively relaxed pressure from predators here. My conceptual framework concerning ‘baffle-organs’ is consistent with this observation.
Just to clarify further.
Aposematism warns of a particular hidden weapon. This aposematism can, of course, be FALSE in the sense of a Batesian mimic that pretends to have a particular hidden weapon; the butterfly faunas of the world are full of examples of this. The point is that aposematic mimicry may be a lie but it’s informative nonetheless, and a predator can overcome the disinformation by learning to recognise the trick. The tactic deployed by Tiliqua and Chlamydosaurus is not aposematic, because there is no hidden weapon either true or false. There is nothing, and indeed there is worse than nothing, there is a waste of time, attention, and cognition from which NOTHING CAN BE LEARNED. Once predators figure out that these lizards are simply BULLSHITTING, as opposed to telling lies, then the game is well and truly up and such creatures should go extinct promptly.
http://www.yallaroo.com.au/images/Blue-tongued.JPG
http://www.runwildtv.com/wordpress/wp-content/uploads/2013/01/Tiliqua-nigrolutea-007.jpg
http://www.arod.com.au/arod/pictures/squamata/scincidae/tiliqua/Tiliqua-rugosa-thumb.jpg
http://cdn2.arkive.org/media/94/946D038A-D7D4-4D8D-8FF0-398FA5809F95/Presentation.Large/Adelaide-pygmy-bluetongue-skink-side-profile-with-mouth-open.jpg
http://en.wikipedia.org/wiki/Pogona
(writing in progress)
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