Pinup: Oct 2, 2016 (Finally Mermaids)

[partner555 170]

https://www.patreon.com/posts/double-finally-6903842

[CritterKeeper 1,102]

Silly me, I was too busy being happy Dan gave them tails with no scales and with the flukes in a dolphin's horizontal orientation, which always made more sense to me than trying to mix mammal with fish.

[Don Edwards 548]

Most of the mermaids I've seen had horizontal flukes rather than vertical fins. Scales, however, are unfortunately common.

I've also seen a few with vertical fins AND GILLS. Which makes sense. (The issue is that to support a typical mammal metabolism, which is a prerequisite to supporting a human brain, the gills would have to occupy about half of the torso, and they couldn't shove enough water through a human mouth and throat. But then, with magic...) It's thought that the main advantage of horizontal flukes, for aquatic mammals, is that it helps them turn toward the surface faster than vertical fins would; that wouldn't matter much for a water-breather.

[Pharaoh RutinTutin 1,586]

Which one posed for the Copenhagen statue?

[hkmaly 490]

Ok. This can't be that hard to make canon. We only need to show some mermaid movie to them before they visit Tedd ...

5 hours ago, CritterKeeper said:

Silly me, I was too busy being happy Dan gave them tails with no scales and with the flukes in a dolphin's horizontal orientation, which always made more sense to me than trying to mix mammal with fish.

Trying to mix mammal with fish is definitely bad idea, but there IS precedent of mammal with scales.

3 hours ago, Don Edwards said:

The issue is that to support a typical mammal metabolism, which is a prerequisite to supporting a human brain, the gills would have to occupy about half of the torso, and they couldn't shove enough water through a human mouth and throat. But then, with magic...

If we accept the traditional image of mermaid cities on bottom of sea, I don't think gills would suffice ... the amount of oxygen inside underwater building can't be high enough ...

[Scotty 1,061]

7 minutes ago, hkmaly said:

3 hours ago, Don Edwards said:

The issue is that to support a typical mammal metabolism, which is a prerequisite to supporting a human brain, the gills would have to occupy about half of the torso, and they couldn't shove enough water through a human mouth and throat. But then, with magic...

If we accept the traditional image of mermaid cities on bottom of sea, I don't think gills would suffice ... the amount of oxygen inside underwater building can't be high enough ...

In the Seaquest TV series, there was a character that had been genetically modified with gills in a believe the ribcage area so that he could breath underwater. I can't imagine how they managed to make it possible to go from air breathing to waterbreathing and back again with no issues though.

[mlooney 3,417]

This is nice, but merfolk aren't on of my half human favorites.  Well done and I do like the are half dolphin not fish.

[ijuin 572]

12 hours ago, Don Edwards said:

I've also seen a few with vertical fins AND GILLS. Which makes sense. (The issue is that to support a typical mammal metabolism, which is a prerequisite to supporting a human brain, the gills would have to occupy about half of the torso, and they couldn't shove enough water through a human mouth and throat. But then, with magic...) \

It's not just supporting the brain--it's also maintaining body heat. Water conducts heat away from a warm body much more rapidly than air does, so aquatic mammals retain heat by putting insulation (mainly blubber) under their skin. However, gills (or any other water-breathing structure) require that the water be separated from the blood only by very thin membranes (a fraction of a millimeter). This means that a large amount of body heat will be lost to the water. Replacing that body heat will require even more oxygen, which will require more gill area (or faster pumping of the water through the gills), which will result in more heat loss, which means more heat replacement, etc. in a vicious cycle, resulting in ultimately needing more calories than are feasible to acquire. For comparison, humans on land spend nearly half of our rest metabolic rate on replacing lost body heat (and the fraction is even higher for small mammals--the smallest rodents can spend over half their body weight in food per day on it).

TLDR: In sum, water-breathing loses too much body heat to the water for a warm-blooded water breather to be practical.

[Stature 96]

Took a few polls and 12 years (well, the iconic one). Where have those days gone?

17 hours ago, Pharaoh RutinTutin said:

Which one posed for the Copenhagen statue?

Left.

[Sweveham 65]

Yay Mermaids! I like mermaids. Ellen's and Nanase's sheer joy here is also wonderful. They look happy to be together, happy to be mermaids, which they damn well should be.

 

[hkmaly 490]

14 hours ago, ijuin said:

However, gills (or any other water-breathing structure) require that the water be separated from the blood only by very thin membranes (a fraction of a millimeter).

It works very similarly in lungs, but lungs are INSIDE. Very important function of all those breathing pipes (trachea, bronchi, bronchioles) is to warm the air while going in and warm the pipes when it goes out.

It would be much harder to do something similar with water because water is incompressible so it's harder to get it through any pipe.

15 hours ago, ijuin said:

Water conducts heat away from a warm body much more rapidly than air does

I think this is technically incorrect. Metals have hight conductivity and therefore get the heat away from you faster. Water have just higher thermal capacity. It only get the heat away from you faster if you or the water are moving. Of course, generally fish and aquatic mammals DO move.