One of the (many) reasons I was so excited to spend six months in Australia was the mindblowing diversity of endemic herps (i.e. amphibians and reptiles this country houses, most of which I had never seen in real life before. As you might have guessed, my mind was already bent on observing some of Australia’s famous elapid snakes, such as taipans and Eastern browns. However, I would soon come to realize yet again that there is much more to wildlife than “mainstream” charismatic species- and I do mean “soon”.
Flash forward to last week’s Monday, my first day at the Venom Evolution Lab here in Brisbane. As if the idea of spending a whole semester there doing research on snake venomics was not enough to process, at some point my coworker James (whom I had literally just met) asked: “Would you like to join us for some herping tonight? We’re going to a great rainforest spot nearby”. Honestly, do I even have to tell you the rest? As soon as work was dealt with for the day, I rushed home, put on my field clothes and boots, grabbed my camera, and off we went.
It takes an hour to drive from Brisbane to the site James wanted to take us to- “us” as in myself, our lab colleague Abhinandan (or Rocky, as we like to call him), and South African herpetologist Chad, who was looking to make the most out of his trip down under after a conference in New Zealand. When we arrived, it was almost dark already- our eyes would soon be completely useless without a flashlight (which I had to borrow from James, since I was foolish enough to forget mine at home). However, the astounding variety of life forms that inhabited the forest was giving us ample notice of its presence- by means of sound. Cicadas, frogs, bats, and most likely countless other animals I wasn’t able to identify by their calls sure weren’t holding back- an orchestra so chaotic, yet so soothing and humbling to listen to. Anyway, I can imagine you are getting tired of my tirade and asking “where is the wildlife?”, so let’s jump to the moment our eyes noticed a tiny glowing dot on a tree trunk along the way.
Believe it or not, this was one of the creatures I was hoping to find the most here in Australia- where they are extremely common. In this picture you can admire a brown huntsman spider (Heteropoda jugulans) in all its glory. If your first thought when you saw this was “burn them all” or something on that line- boy, we have work to do. Spiders are incredibly fascinating animals, and huntsmen particularly so if you ask me. These arachnids (family Sparassidae) are miles away from our standard idea of a spider: they don’t build webs but chase down their prey and/or lay in ambush instead, relying on their extraordinary agility and speed; they hunt by sight, their eight eyes arranged in two rows of four each that glow in the darkness of the night; and they can get big. Like, really big. This species is not particularly large (and many others are downright tiny), but some of these spiders- above all the giant huntsman (Heteropoda maxima) found in South-East Asia- can attain ridiculous leg spans of nearly 30 cm. Again, I understand that you might not care about any of this at all, so I shall get to what I presume is your main concern- no, this spider is not dangerous to humans. Sure, big huntsman bites do hurt from what I know (no personal experience, luckily), but they most definitely won’t kill you. Still not convinced? I suggest we look at the bigger picture.
Spiders number in the thousands of species and are found in all continents except Antarctica. They have adapted to nearly any land biome known to man- and even freshwater, for that matter- and many of them thrive even where humans have altered the landscape to the utmost level. These animals are able to produce one of the most resistant and flexible materials in the world that we haven’t so far managed to replicate to the same degree- even with our supposedly superior intellect and technology. Spider-like arachnids have been crawling on all surfaces of our planet since the Silurian (i.e. over 400 million years ago), when vertebrates didn’t even exist at all. Besides, despite our hate and fear towards them, spiders provide us with an invaluable pest control service- their appetite is truly voracious, as they often eat tons of insects on a daily basis. It is not for me to persuade or force you to like spiders- all I’m asking is that you treat them with the respect they undoubtedly deserve.
After taking a few pictures of this stealthy eight-legged predator, we moved on down a small staircase that led us to a stream. The water level was as low as can be, which allowed us to spot tiny fish swimming around- and a couple of big eels too, which were a welcome surprise. Bats and cicadas were still keeping us company with their calls while the temperature was getting cooler at a steady pace- a pleasant relief from the scorching heat of the day. Chad, a proficient photographer, was taking shots of pretty much anything that moved, while Rocky and I were amazed by James’s ability to instantly identify any of said creatures to species level- be it ants, spiders, or frogs. Speaking of James, there was a reason why he had taken us to that specific place- that reason being, simply put, this.
You can see it, right? Because I must admit, it took me a while to locate it on the trunk of that tree while the others were pointing at it trying to guide my eyes. This otherworldly animal is a Southern leaf-tailed gecko (Saltuarius swaini), the first of more than 10 individuals we encountered that night. Since there is no scale on the picture, allow me to say that these geckos grow quite large- around 20-25 cm from what I’ve seen. This one was no exception, yet its mindblowing camouflage skills allow it to blend perfectly with the tree bark substrate. Once again, we see evolution at its absolute best- I am no gecko expert, but I dare to say that such a striking resemblance to the surroundings enables this species to go largely undetected thanks to cryptism- a formidable resource to avoid predation.
To some of you, the name “leaf-tailed gecko” might have rung a bell- which brings to me an important geographical distinction to be made here. In fact, species of the genus Uroplatus, endemic to Madagascar, are also referred to as “leaf-tailed geckos” for the very same reason- they bear a striking resemblance to tree leaves and bark. However, the Australian and Madagascan leaf-tailed geckos are only distantly related in phylogenetic terms, making it extremely unlikely that their phenotype (i.e. appearance, roughly) is the ancestral state for the group. Instead, it is safe to advocate that the two genera evolved their phenotypes independently to face similar selection pressures in their habitat. This phenomenon, widespread across the entire animal kingdom, is usually referred to as “convergent evolution”, although both the label and the definition of the concept itself are still subject to debate (see this paper for an overview). I always refrain from using the word “perfection” when talking about evolution to avoid any hints of teleology- which has no place in the theory itself- but adaptations of such caliber as these truly leave me speechless sometimes.
Once we got the hang of it, we started spotting leaf-tailed geckos everywhere- on trees, on the ground, on rocks, you name it. However, these lizards share the area with countless other animals- some of which we got to bump into as well. Particularly amusing to me were the barred frogs (Mixophyes sp.) casually hopping on the ground as we passed by their hides. Frogs always have that quirky, adorable appearance- they are basically huge mouths with legs, which I find oh so funny. However, these amphibians have a voracious appetite as well- barred frogs are the largest native anurans in this area (only the invasive cane toad surpasses them in size), and their presence in large numbers is usually an indicator of a healthy ecosystem. This holds true for amphibians in general, as these animals are often highly sensitive to even minimal disturbances in their habitat due to their semi-permeable skin and specific humidity/temperature requirements. Thus, spotting quite a few of these chubby frogs was a welcome sight for us- also because some individuals such as this one showcased a beautiful banded pattern around their hind limbs, whence their common name comes from.
After three hours of herping around, it was time to drive back to the city. We walked out of the forest, still careful not to miss any animal we might find along the way- I mean, a snake or two would have been a welcome surprise, am I right? Unfortunately though, no luck in that sense. Oh well, no big deal- now that I’ve had a taste of what the forests of Queensland have to offer, I can’t wait until the next nocturnal herping trip. No guarantee that I’ll manage to see any of these creatures again- but they most definitely will be there.
Because the night belongs to them.