Blargg's Identity (Lava Dragon or Elemental Spirit?)
A very uncommon enemy nowadays, Blargg, the lava dwelling yoshi-esque dragon appears only in 8 games, perhaps even more or less depending on your definition of blargg.
And confusingly, almost all it's appearances use a different design. In Super Mario World, it takes on the appearance shown above, and retains this look in Mario & Wario, as well as Super Mario RPG, sort of.
Super Mario RPG features not "Blargg", but the Czar Dragon (pictured below), a blargg-like creature made of smaller fire-like enemies named Lava Bubbles. Perhaps this is just a specific blargg named Czar Dragon, or a mimicry of a blargg made by lava bubbles used to scare off intruders?
And finally there's Blargg in the Yoshi's Island series, possibly the biggest departure from it's original design by far. It is instead named "Gargantuan Blargg" here, being larger than normal. It looks like another enemy in the game, Nep-Enut, a water dwelling creature, instead of it's usual dragon-like form. (Gargantuan Blargg and Nep-Enut shown below)
They look even more odd in Yoshi's Story, but still more akin to the Yoshi's Island version, shape-wise and size-wise. (shown below)
So is this the same species, or just a different creature altogether with a similar name? In the real world, animals are given names based on other things they resemble despite not being in the same genus, but perhaps there's something deeper here that makes the former idea stay true. These might all truly be "blarggs" after all, not just in name alone.
It seems nep-enuts are actually composed of water, as shown in some games, and blargg in Yoshi's Island is shown as being made from lava as well. And as I mentioned already, it's also shown Czar Dragon is made of smaller fiery creatures. With this information I have a theory...
The Elemental Theory
It's possible every creature mentioned here are simply elemental spirits, using elemental matter as their bodies. They usually assume the standard ghost-shaped form in Yoshi's Island (which seems to be their modern design nowadays), but also taking on a more dragon-like shape in Super Mario World. That game is chronologically set after the Yoshi series, so it's possible the spirits "learned" how to appear more dragon-like over time. But this is merely my personal idea of how it may work.
Another point of proof to this theory though, is the existence of another "blargg", also in Yoshi's Island, called a Blarggwich. (shown below) This seems to be a "non-elemental" version of a blargg, as seen by the fact that it's a colorless, phantom-esque creature that simply ferries around the player. Perhaps when elementally charged (like the spirits in Luigi's Mansion), they become the creatures we know as blargg and nep-enut.
Addendum
This is a shorter post, I wanted to talk about Blargg because I recently realized how inconsistent it's design is, and how strange it is that it barely appears anymore in any core Mario game. I also just like talking about lesser known Mario things, so this was an excuse to do that, thanks for reading!












