Part 1: Snake or lizard???
In my part of the world we are seeing an increase in snake presence. This is probably because the snakes have taken note that the days are getting shorter and colder and they need to get their affairs in order before winter. Warm spots are also at a premium so they become bolder in order to secure their own, very literal, place in the sun. We start seeing them basking on the roads or on footpaths often in areas that humans frequently inhabit. This is of course going to translate to a fair amount of angst on the part of the humans. So I thought I should tell you a bit about the creatures you’re seeing around the place.
This article is not going to chide people about killing snakes (you probably shouldn’t but that’s a topic for another day). Instead, I want to show you exactly what the wriggling creature in front of you could be and it may not always be a snake.
Know your wriggle things
Anyone who has read my previous articles will know I’m always on about how amazing and beautifully complex our natural world is and that nothing is ever simple. This philosophy extends to snakes. It is very true that Australia is home to many of the deadliest (taking venom potency and temperament into account) snakes in the world. What is not so often mentioned is we’re also home to many, many harmless species of snake. We also have an entire family of legless lizards (Pygopodidae) that even to a trained eye, look snakish (real technical term).
What makes a snake a snake?
If you’re walking along and shout, “F&^% SNAKE!”. What were the identifying features that lead you to the conclusion that it was a snake? Well you’d probably say a combination of the following: wriggled in an a sort of ‘s’ shape; had a long, thin and cylindrical body; forked tongue and had scales. Seems a pretty decent definition of a snake so let’s roll with it for a moment.
Would you say that this creature is a snake?
Let’s defer back to the definition of a snake we used earlier and apply it:
Now let me blow your mind…. It’s actually a lizard. In fact it is a Burton’s legless lizard (Lialis burtonis) also known as the snake lizard for obvious reasons. Burtons are a legless lizard rfom the family Pygopodidae and are completely harmless to humans. Unless in some strange series of events you manage to get a live one stuck down your trachea and you end up suffocating. Other than in outlandishly unlikely occurrences, a Burtons probably couldn’t hurt you if they tried and they probably wouldn’t even try. The most aggressive behaviour I’ve ever seen from one, was a little bit of hissing and opening its mouth in what it thought was a threatening gesture. The result was actually hilarious and everyone laughed at it (poor thing).
What about this wriggling creature then?
That is a coastal taipan (Oxyuranus scutellatus) and I recommend getting far far away immediately and you should consider inventing a time machine so you can undo the actions that led you to that situation. Sometimes the thing that looks like a snake is in fact a snake and you may be in a spot of hot water…. If you don’t know 100% if the creature in question is venomous then treat it as if it was venomous and keep your distance. It’s best to keep your distance regardless because these are wild animals and not only is their behaviour hard to predict but by getting close you are massively stressing them out.
Legless from evolution not from consumption of alcohol
Now the Burtons is instantly identifiable because they look like the offspring of a crocodile and a snake. This is in reference to their very pointed snout much like a crocodile’s. There are an additional forty separate, individually distinguishable species of pygopod lizards (from the family Pygopodidae) in Australia and PNG. Some of these really do look like snakes. Take the excitable delma (Delma tincta) as an example….
At this point I am sure many readers will be shaking their heads saying that scientists are crazy and that’s clearly a snake. Pygopods are an excellent example of why we can not group animals together based on their appearance alone. In fact, Pygopodidae are more closely related to geckos than snakes. Pygopods in fact share many characteristics with geckos. For example, they both lack eyelids and keep their eyes moist by licking them with their thick, fleshy tongues (note: not acceptable table manners for humans but nevertheless an impressive feat).
Pygopodidae translates to, ‘rump foots’. This is in reference to the absence of their forelimbs but presence of hind feet. The hind limbs are usually reduced to minute paddle-like structures. They are often so tiny that they are nearly invisible to the human eye. This is how they became known as legless lizards even though they do technically have hind limbs. This is why I have been referring to the members of Pygopodidae as pygopods rather than as legless lizards.
Pygopods can be distinguished from snakes by the presence of these hind limbs. However, if you’re trying to work out if an animal is dangerous or not by picking it up and examining it with a magnifying glass, you’re kind of defeating the purpose…
The best way for a lay person to determine if the slithery thing is a snake or is a lizard is by the snape of the snout. Pygopods have pointed snouts and snakes tend to have relatively rounded heads. Burtons have a severely pointed snout and this characteristic is also present, albeit to a lesser extent, in other pygopods.
Pygopods have external ear openings whereas snakes do not. Sometimes these ear openings are very small, such as in the case of the Bronzeback (Ophidiocephalus taeniatus), but they are still present. They are also capable of rapidly regenerating their tail if it becomes detached just like a gecko can. However… please, please, please do not start cutting off animal tails to determine if it is a snake or a lizard.
Snakes do not have any limbs but they do have a body. Most people think a snake is all tail but then where would they fit their organs? Herpetologists (scientists that study things that creep i.e. lizards and snakes) use a set of standard measurements to compare species. One of these measurements is the snout to vent length. This is the distance from the tip of the animal’s nose to its vent. The vent is an opening that allows the passage of waste. The tail length is equal to the length of the animal minus the snout to vent length. A less confusing version is that the tail is measured from the vent to the end of the tail. If the tail is equal to or greater than the length of the snout to vent then the specimen is a lizard. If the tail is shorter than the snout to vent length then it is a snake.
There is also a difference in how snakes and pygopods locomote. Snakes are extremely mobile and are essentially a muscular spaghetti with very few limitations in what they can make their bodies do. Pygopods however, initially evolved with legs and later branched off into their own family that lacked limbs. This means their skeletal system and muscle attachments developed as such. If you were always going to be a noodle you’d go out there aiming to be the best noodle you can be. However, if you wanted to have four legs and then at the last minute decided you wanted to be a noodle too, you’re probably not going to be the best noodle out there… My apologies to Charles Darwin for that explanation. What I mean is that in the olympics the snakes are going to outdo the pygopods (sorry pygopods but its true). Snakes can utilise muscles that are simply not present or not used in the same way as in pygopods.
Cogger’s Three rules:
Cogger (amazing scientist that developed an incredible reference book on Australia reptiles and amphibians) has three rules to determine conclusively if the animal is a lizard:
- if limbs of any kind are present, no matter how small, then the specimen is a lizard
- if the tail is about as long as or longer than the snout-vent length the specimen is a lizard
- if an external ear opening is present then the specimen is a lizard
Internet in all of its inaccurate glory
If you google, “how to tell the difference between a legless lizard and a snake” multiple people will proffer up their opinions. Too often these opinions could not be more inaccurate. Sometimes I wonder how they manage to come up with some of the ideas…
Myth 1: legless lizards have eyelids and snakes do not
This is severely incorrect, at least when it comes to Australian species. Think of pygopods as snake-like-geckos rather than lizard-like-snakes. Geckos lack eyelids so they are constantly licking their eyeballs to stop them drying out. The same goes for pygopods.
Myth 2: snakes are just one type of legless lizard
Okay…. hard to know where to start with this one…. Snakes are from the Order Squamata (they have scales), Suborder Serpentes (snakes). Lizards are Order Squamata (scaly), Suborder Sauria (lizards). There are then multiple families within the individual suborders. One of the families under suborder Sauria is Pygopodidae (legless lizards). So no, snakes are not just a family of legless lizards. Not even close.
Myth 3: snakes are venomous and lizards aren’t
Whoever came up with this one has probably entered themselves into the Darwin Awards. This is because 1. some lizards are venomous 2. not all snakes are venomous.
Myth 4: only snakes have a forked tongue
This one I can kind of understand but it’s technically not accurate. There are lizards with forked tongues even if this fork is only very slight. I would personally consider the Burtons to have a forked tongue even though the fork is very small. Others may disagree with me but I can definitely see a fork in there even though it’s not akin to the traditional image of a forked tongue.
Myth 5: if it flicks its tongue out constantly it is a snake.
Nope… nope…nope… I recommend spending some time in the garden watching bluetongues or other skinks and this one will quickly be disproved. Lizards are constantly flicking their tongues around. So do cattle actually but I’m not about to call one of them a snake.
Myth 6: if it has a spine it is a lizard
Lizards and snakes both have bones which include a spine. If you watch a bone breaker dancer you would seriously question whether they had bones. They move with great fluidity that creates the illusion of lack of bones but they are there. Same goes for a snake.
Danger noodle ahead!
If there is in fact an actual snake ahead it’s best to stop moving and then back away slowly. No quick movements and you’ll be fine. If you absolutely have to go that way then once you’re several metres away stamp the ground a few times. The snake will get the idea and then wriggle away. If it doesn’t move on it’s probably best to reconsider your route. Do not throw sticks and stones because snakes have bones and you will hurt them.
If you see a wriggly thing it could be a lizard or a snake or maybe a giant worm (a topic for another day). If it’s pointed at the front end, probably a lizard. If it has a hole in the side of its head (external ear opening) that is meant to be there, then it is a lizard. If it has limbs, even little teeny ones, it is a lizard. If it is venomous it could be a snake or a lizard. If its tail is equal to or greater than the length of its body then its a lizard. If you don’t know do not touch it or go near it. If you don’t need to touch it, don’t touch it.