On the rare occasion that the mainstream media talk about amphibians, the coverage tends to take on a sensationalist tone. Even when the aim of a news story is to highlight an important issue like the threat of extinction, the headline invariably seeks to shock: “World’s weirdest amphibians”.
Obviously, some species capture the public’s attention in ways that others can’t. For example, when a boy from Kyoto came across a rare giant salamander on his way home from school, it was inevitable that it would become a news item. The clickbait title writes itself: “The Appearance of a Giant Semi-aquatic Monster”.
Rare, surprising and remarkable – yes – but let’s drop the ‘weird’ and focus on what makes these species wonderful.
This diverse order of amphibians (Urodela) boasts more 600 individual species, each fascinating in their own way.
Welcome to the wonderful world of salamanders!
Species of reference around the world
When we hear the word salamander, most of us imagine one of three species.
If you’re reading this in Europe, you’re most likely to picture the fire salamander. Black with bright yellow markings and about 15-25 cm long, this salamander is found across southern and central Europe. The vivid colouring serves as an aposematic signal, warning potential predators of its toxicity.
In the western hemisphere, common to much of North America, is the tiger salamander. This species belongs to the mole salamander family (ambystomatidae). In the wild, they live in burrows underground and are rarely seen in the open. However, they have become a popular pet in the US and, in captivity, they can live for up to 25 years.
Another well-known member of the mole salamander family is the critically endangered axolotl, also known as the ‘Mexican walking fish’. While this species is endemic of Mexico and does walk around at the bottom of a lake, it certainly isn’t a fish!
It’s an example of a neotenic amphibian, which means they reach adulthood without undergoing metamorphosis. One indication of this is that, instead of growing lungs like most other salamanders, they retain external gills on the sides of their heads.
10 families of salamander
Salamanders have been around since the late jurassic period. In that time they have evolved in different ways, in different parts of the world, to fill different ecological niches. In terms of taxonomy, there are 10 families of salamander. Here they are, along with their common names.
|Dicamptodontidae||Pacific giant salamanders|
|Proteidae||Mudpuppies and olms|
|Salamandridae||Newts and true salamanders|
Salamanders vs. newts
I have a particular interest in the names we give to wildlife, where these names come from and what they say about how we perceive the natural world. Most languages have distinct ‘labels’ for salamanders and newts, but how exactly are they different?
Well, it’s a bit like asking what the difference is between anacondas and snakes. That is, newts are salamanders. More specifically, a salamander may be referred to as a newt if it belongs to one specific subfamily: pleurodelinae.
Besides that, newts tend to spend more of their adult lives in water. However, as we saw with the axolotl, there are exceptions (terrestrial newts and aquatic salamanders).
Hellbenders, sirens and olms
With this being a brief introduction to the world of salamanders, we can only hope to scratch the surface. After all, there are hundreds of different species. Therefore, I’ve selected a three more salamanders to represent each suborder.
Next, we have another aquatic salamander, the siren. There are just two remaining species belonging to the genus siren, the lesser siren and the greater siren. And another two species of dwarf siren. All species of siren live in the Southeastern United States.
Sirens have long, eel-like bodies and, similar to the axolotl, they have external gills. Besides their body shape, what makes them distinct from other salamanders is that they lack hind legs.
Their dark environment means that good sight provides no selective advantage. They appear not to have eyes at all but, in fact, they are simply covered over by skin. This adaptation causes them to be blind, but they retain some photo-sensitivity and always swim away from light.
To compensate for their lack of vision, the ‘snout’ on the the olm’s head is packed with highly sensitive chemoreceptors, mechanoreceptors, and electroreceptors.
Remarkably, these salamanders can live for more than 100 years.