Giant salamanders - May 16

 Obligatory disclaimer: real life sucks, but we're going to talk about a RL animal altogether, since Marvel and co. are lying low for the rest of May. Therefore, where are we?

Let us talk about the cryptobranchid, or the giant, salamanders of Asia and North America, simply because they are in their own suborder. Pause

There are three suborders of the tailed amphibians, aka newts and salamanders, and the overwhelming majority of them belong to the Salamandroidea suborder; the only exceptions are the sirens of the south-east North America, (USA), and the aforementioned giant salamanders and their relatives, (more on them below).

The sirens’ differences from the rest of the salamanders are obvious: they are probably the most neotenic of all the tailed amphibians: not only they have external gills, but they also have only front legs – no hind ones. Pause.

Whereas in frogs and toads it is the hind legs that develop first, in newts and salamanders it is the front ones instead; plus, their tadpoles have external gills, while the frogs and toads acquire internal ones very quickly; the legless caecilians, the final group of the modern amphibians, also seem to have external gills, but they are much less known than the other two, so they will be mentioned only in passing – wait.

Getting back into the mists of time, the thing is that the modern amphibians only began to appear around the time of the K-T extinction 66 MYA; before then, especially during the Palaeozoic and the early Mesozoic, completely different groups of amphibians ruled. The thing is that while initially paleontologists went with a linear P.O.V. and proclaimed that amphibians evolved from the fish, and reptiles – from the amphibians, by now it is clear that these statements are much vaguer than scientists have initially imagined.

Yes, the initial land vertebrates have evolved from fish, (as there were not any other vertebrates), but these days scientists tend to classify those early semi-terrestrial semi-aquatic animals as ‘tetropods’ and prefer to differentiate them from the amphibians because of reasons. Ditto, right now the actual ancestors of the reptiles is unknown; the reptiles have appeared back in the Carboniferous, (as shown in ‘Walking with Monsters’, for example), though they were small at that time – about the size of the modern lizards on average, (but, again, they weren’t really related to the modern lizards and snakes at all); yet they were already differentiated from the amphibians. However…

However, for a while, in the late Paleozoic, there were the so-called reptilomorph amphibians – amphibians that had reptile-like traits in adults, but their young still had gills and lived in water… and why should not they? The amphibious way of life – when the young and the adults of the same species have different… everything and thus do not compete with each other – is clearly advantageous, as the amphibians’ evolutionary history, from the Devonian to Recent demonstrates; however…

However, somewhere along the line, things have diverged at least for some tailed amphibians, as they evolved neoteny, a condition where juvenile traits persist into sexual maturity. Actually, neoteny is present in several groups of animals, including insects, so let us for now focus on the tailed amphibians: for them, neoteny is when a species has both sexual maturity and external gills, (with the sirens going one-step further, as we already said). However, the giant salamanders are a different story.

Why? Because while they are mostly aquatic, (as the neotenic amphibians are), their adults lack external gills. Yes, their young hatch underwater, have external gills, eventually grow legs…but unlike the axolotl and the mudpuppies, their gills disappear with sexual maturity; instead, they grow skin folds and the like to extract oxygen from the water instead, which is a different story altogether – but what it is?

To recapitulate, metamorphosis came before neoteny – for a while, there was no obvious reason to evolve the latter, but when it did… either the giant salamanders were too late, apparently, as plenty of other salamander groups and subgroups had, and so the giant salamanders couldn’t ‘fit in’… other the giant salamanders were too early: they began to stick to a mostly fully aquatic lifecycle before the other salamanders evolved neoteny, and since there was no competition, they flat-out didn’t evolve it, as there was no need for it. What next?

While throughout Earth’s history there were plenty of giant salamander subgroups, right now, there are only three species around – one in North America, and the other two in Asia. The American hellbender is the smallest of the three – no bigger than 70 cm long, about the size of a small child at best… but the bigger species of North American mudpuppies don’t grow over 48-50 cm long, so, obviously there’s some other factor at work, since the Japanese giant salamander reaches 150 cm in length – the size of a small adult – and the Chinese species – reaches 180 cm, which is the size of an average adult instead. Pause.

Let us get into the ecology of the giant salamanders instead. While they might be vaguely associated with the crocodiles, they really are not. The crocodilians divide, among other ways, into two broad categories: narrow-snouted fish-eaters and broad-snouted ambush-hunters of land animals. By contrast, the giant salamanders live most of their life underwater, and they do not ambush land animals, yet their heads and snouts are shore and broad instead. Therefore, whom do they resemble instead?

Why, the catfish, and especially the wels catfish – one of the biggest freshwater catfish species of them all. Just as the giant salamanders, the wels catfish is active mainly at night; it hunts by swimming along the river bottom, sensing the prey with its whiskers and swallowing them whole. The giant salamanders’ don’t have such as advanced whiskers as the wels catfish does, but neither does the burbot, (another fish), and it does the same thing too, but being around 1 m 24 cm in length, (in the size range of the giant salamanders, cough), it just cannot compete with the wels catfish size-wise. Where are we?

Ah yes, entertaining my theory that the giant salamanders, (also known as the ‘primitive salamanders’ in some nomenclature, while the other, non-siren salamanders, are known as the ‘advanced salamanders’ instead), are the ecological analogues of the wels catfish instead. The hellbender lives in the Eastern United States, where there is not any natural analogue of the wels, and, again, it is the smallest living member of the cryptobranchids. The Japanese giant salamander lives alongside the Biwa catfish – a wels catfish variant… which is endemic to a single lake only, and the Amur catfish, which is around the size of a large burbot instead, so the Japanese giant salamander can handle it.

As for the Chinese salamander, this is where things get murky. These days, there are actually two species of this amphibian: the Chinese salamander proper, and the South China giant salamander; both species are critically endangered, (i.e., in a much worse state than their Japanese and U.S. cousins), and there may be more species of the giant salamander living there – they just have not been identified and confirmed by the scientists yet. Still, the Chinese giant salamander species’ complex is struggling – from habitat destruction, water pollution, harassment from humans, hybridization with the Japanese giant salamander…and maybe from the competition from the introduced wels catfish? Who knows!

One last thing. The kappa. In one of the RM episodes, our main man JW went to Japan to confront the Biwa catfish and the Japanese giant salamander, which he proclaimed to be the root behind the kappa legend. With all due respect, JW, but on this occasion you’re a flat-out wrong; the kappa was never depicted as even vaguely salamander-like, but as a turtle-like humanoid instead. Therefore, that is that.

For the moment, though, we are saying good-bye to the giant salamanders. See you all soon!