Last night I had a conversation with my friends Bobby and Claire regarding mermaids. Claire remarked, “You know what I don’t get? Why do they have belly buttons?”
“It’s an umbilical cord thing.” Bobby offered.
I shook my head and, from there, we launched into a discussion of whether they would be warm or cold-blooded. The above exchange, by the by, is why my friends are awesome. It also is the tip of the iceberg concerning why mermaids are really, really implausible. Even if we were on a different planet with a different environment and followed a different evolutionary path, mermaids, as depicted, wouldn’t make any sense.
First off, let’s start where Bobby and Claire began: the belly button. A navel indicates the attachment point for the umbilical cord. This, furthermore, indicates that mermaid would bear live young, like mammals. Plausible, I suppose, but it puts mermaids in a really peculiar evolutionary category. Fish lay eggs; fish are also cold-blooded (ectothermic). Mammals bear live young; mammals are warm-blooded (endothermic). Mermaids, ostensibly, are some kind of hybrid. So, are they ectothermic creatures who bear live young? If so, why? These things tend to happen for a reason, if indirectly–a species happens upon a particular adaptation that serves them well and, therefore, survives (that’s how evolution works, essentially). Now, ectothermic creatures are comparatively simplistic organisms–they lack (and don’t need) the various complicated systems we endotherms use to regulate our own internal temperature. One of the reasons we mammals bear live young is that it takes a longer period of time for an endothermic embryo to develop to the point where it will survive on its own–you can’t typically leave something like that in an egg and have it work out (the exception, of course, being the ever-bizarre platypus). Cold blood creatures, to my knowledge, exclusively lay eggs. It’s easier and they have no reason to do otherwise. Mermaids would fall into the same category, so then they wouldn’t have belly buttons. They also wouldn’t have breasts, which would instantly make mermaids less interesting to men worldwide.
Now, if they’re warm blooded, that would change how they look. Endotherms need to maintain their body temperature, and the ocean, you may have noticed, can get pretty damned cold. Endotherms that live in the ocean (seals, whales, dolphins, manatees, etc.) combat this problem with thick layers of blubber or fur. Mermaids, really, should be pretty beefy, chunky folks. The Little Mermaid would have had more in common with Shallow Hal than it would have with Cinderella.
While we’re on the subject of bodies, let’s talk about the arms, shall we? The mermaid arm is built like a human arm (and, yes, I realize that mermaids are really just another incidence of anthropomorphism used for metaphorical or thematic purposes, but that’s not my topic here). The human arm is built so as to assist us in lifting, climbing, striking, and, to a lesser extent, grasping. With the exception of grasping, none of those things are really that essential in a watery environment. Mermen certainly wouldn’t have any cause to develop the muscular torsos so often seen in illustrations, anyway. They’d be better off with tentacles, which are better at grasping than hands, and grasping well is what you’d want. I suppose those arms are handy for pulling yourself along on shore, but mermaids don’t seem to do that often, except to tempt sailors to their doom or some such, and that seems a pretty niche purpose for so complicated an appendage. Stranger stuff has happened in nature, but it raises doubts, right?
I don’t really need to go much further, do I? I mean, why do they wear clothes (or, if they need to, why wouldn’t they wear much more)? Why do they have eyelashes? Why would they wear their hair long? Are they really amphibious and, if so, why? Shouldn’t their eyes be better adapted to see in the dark? Man…the problems go on and on.
If you wanted intelligent creatures of the deep, I humbly submit these guys, whom I cooked up a while ago and have thought about at length since. There’s your merpeople–squids, not hominids. Creepy and slimy and maybe beautiful, with not a seashell bikini top to be found.