Long ago there was this movie named Waterworld [link]. A lot has been said about it, including that it almost wrecked Kevin Costner’s career. Won’t go into that. The idea is that there has been some kind of cataclysm and the earth is almost 100% covered with water (they say it’s the poles melting, but that’s physically impossible, there’s not that much frozen water). The main character is a mutant, since the human species is adapting to its new environment developing gills to breathe underwater.
In case I am being too geeky here, gills are the breathing structures that fish have. They are composed of very delicate filaments that take care of the exchange of oxygen and carbon dioxide in the water. They are the fish equivalent to the alveoli in the vertebrates’ lungs. I’ll spare you the biology details, you can read up on them here [link].
The problem I’ve always had with Waterworld is that while some animals have adapted gills to be able to stay emerged (and even breathe through them to some extent), they need a great humidity to remain functioning. Basically, not to dry out and fall. Amphibians are generally slimy and on the smallish side to keep that humidity; furthermore few animals are truly simultaneous amphibians.
Enter elves. Yup, elves. Pretty humanoids with pointy ears. Think LOTR [link] or Dragonlance [link]. Okay, let’s be honest. Think Dragonlance. Dragonlance had sea elves. Really. Guess who was hooked (three guesses and first two don’t count). Nothing was ever explained about their anatomy, but as far as I remember they did not have gills. That meant that they breathed in water as they breathed air.
Which biologically would not work, unless they did the lung equivalent to throw up every time they emerged. Ew.
Let’s imagine for a while. Let’s think… Coral Reef Elves anatomy (Reef elves for short). Reef elves are not featured in any fantasy world that I am aware of (read: I’ve been making this up as I go =D) and the presented facts are only based in my imagination and loosely interpreted biology. I am sure that there are 1001 reasons why this does not work, but I had a blast doing it. I’ll try to keep the big words to a minimum too.
The first point is separate the emerged and submerged breathing. Let’s say that the emerged process (i.e. breathing air) is identical to the human one. You know the drill. Take a deep breath. Keeping it simple, air comes in through nose/mouth, goes down the throat arrives in the lungs, oxygen in, carbon dioxide out, exhale, and air comes right back up the same way [link].
To keep the lungs dry while breathing underwater we’d need an independent breathing system.
A reef elf breathes air the same way a human does. How do they breathe underwater? The first step is filling the nasal cavity (1) with water and close the throat (2). A ring of muscles contracts and relaxes depending on the environment (haven’t quite figured this one out yet. Pressure maybe? I am thinking that the original contraction/relaxation is voluntary and the muscle just stays that way, but I like the pressure/involuntary angle too.)
The nasal cavity of a reef elf (1) is bigger than the human one, and is filled with gill-like structures. The teeth (3) and the jaw are smaller than in a human, as is the tongue (4). The front base of the skull (5) which has a name for sure, but we agreed on not too many big words, is wider than in the human, and spongy, intertwined with blood vessels to carry out the gas exchange. The frontal lobe of the brain (6) rests upon it, like in a human. Thus the oxygen-rich blood reaches the brain first and then is pumped towards the rest of the body.
The elf breathes through their nose. The gills in the nasal cavity (1) and the muscles in the inner part of the throat (7), draw the water in. The gills trap the oxygen and let go of the carbon dioxide, and the water is exhaled through the mouth. This has to be a continuous effort, or at least much faster than the air breathing, since the cavity’s capacity is much smaller than the lung’s capacity.
Other consequences – aside from the obvious presence of the gills:
- Small mouths, pointy chins
- Smaller mouths have less space for saliva glands, thus when on dry land, elves need to drink a lot
- The enlarged mouth cavity and bones (1 & 5) take brain space, thus the brain is slightly smaller than the human brain. Most of the functions seem to be reassigned and there’s no apparent different in average intelligence between humans and reef elves. The smaller frontal lobe’s consequences are:
- Reef elves lack the sense of smell, and some have limited taste
- Reef elves have low sexual drive
- Reef elves are less mentally flexible than humans
- Reef elves are little spontaneous / enthusiast (well, this seems to extend to forest and land elves anyway)
- The skull is more fragile in general than a human one, a punch to the face does much more damage
This system, however, means that reef elves don’t talk underwater, as there’s no air making the vocal cords vibrate. So how do they communicate underwater?
A random fact about reef elves is that they usually have long hair. Many humans believe that they actually breathe through their hair. This is because elvish children are usually brought up on dry land and they haven’t grown their hair yet, as long hair is identified with adulthood.
Stay tuned for a post on reef elvish society (or not, this was the product of an insomnia night XD). Still have a bunch of things to figure out.
Why am I such a nerd, again?