First off, it has to be understood that coastal areas are incredibly rich ecosystems with plentiful resources that could be exploited by a variety of animals, including mammals. As we can see with marine mammals, this has happened before on several seperate occassions.

I cannot see any reason in particular why some sort of primate may not have adapted to better access these resources in a coastal habitat. It’s easy enough to imagine. Some populations of Japanese macaques, for instance, already spend a good deal of time at the seashore, where they play and wash their food. Now, imagine one ventures out a little and picks up some shellfish or crustacean. This becomes a bahavior that others start to pick up, and little by little, the macaques are venturing further and further out from shore, foraging for the shellfish and crustaceans they know are there.

In this case, maybe we will see some mutations that are useful for better enabling the macaques (or other primate, this is just an example) to better exploit the marine resources. So for instance you have one that can hold its breath just a little longer, allowing it better access to more food items in the water. Adaptations such as these may make those individuals more successful and thus carry them over to their offspring. Over time, you start to see features for a more aquatic life.

An aquatic adapted primate would not necessarily have to change dramatically in appearance for it to be successful in this niche. While yes, pinnipeds and whales show pelagic (open water) adaptations such as streamlined bodies, short necks, and lack of grasping forepaws, an animal such as a primate could adapt to an aquatic life without such drastic changes and while retaining some features that could be seen as mermaid like.

A prime example of an animal like this is sea otters. In terms of evolution, they are relatively new to an aquatic existence, yet they are quite well suited to what they do without incredibly dramatic changes appearance wise. I can think of many parallels between sea otters and a theoretical aquatic primate.

For one, an ape would not necessarily have to develop a dramatically different head. Like sea otters, they would likely only need closing nostrils and perhaps closing ears as well, in addition to some ocular adaptations. This would not necessarily change the appearance of a primate’s face too much.

To continue with my sea otter analogy, sea otters also don’t rely on blubber, but rather on thick layers of fur with a waterproof outer layer for keeping warm. This would be easy enough for a primate to adapt in a relatively short evolutionary time frame.

There would also likely be in these “mermaids,” the tendency for the hind feet to become broad and flat for propulsion, as in sea otters. The tail of, say a monkey, might also evolve into a flat, broad tail as well. Again, like sea otters. I don’t even see why a primate of this type would even need to develop fused hind legs in order for people to spot one and come under the impression that they had a fish tail.

The grasping hands of a primate would actually be perfect for such an aquatic lifestyle and there is no real reason why they should lose these. Again, sea otters have highly manipulative forepaws that are useful for a wide variety of purposes. For instance, they can lift rocks or boulders in search of prey, dig in mud, and pluck prey items from kelp. They have even been observed to “hold hands,” probably to keep from drifting away from each other as they sleep. Sea otters can even catch fish with their forepaws. I absolutely think grasping hands would come in handy for a primate evolving to take advantages of aquatic resources.

Considering this, an aquatic adapted primate could find many advantages to its grasping hands when searching for prey. An intelligent animal like a primate could also find ways to use its hands for breaking open shellfish against rocks, or actually reaching into crevices to fish out prey. There is no reason why they should lose this capability and the arms would definitely be something contributing to the mermaid myths and classical images of mermaids.

So actually there are quite a lot of adaptations that would be within reason for something like an aquatic primate, as well as primate features such as arms that could be just slightly modified for this aquatic lifestyle.

A perfect human body upon a fish tail is absurd, but as I am trying to illustrate here, we could have instances of a aquatic adapted primate that may just be humanoid enough in appearance to at least account for some of the Japanese mermaid sightings.

Of course this is all complete speculation. There is absolutely no evidence that this has ever happened, but I’m just trying to present the possibilities that perhaps some people don’t think about. At least in theory, something like an aquatic primate is not completely far fetched.

Anyway, sorry for the long post, and I hope you are at least thinking about the evolutionary possibilities that could lead to what we see in these Japanese mermaid accounts.

However with the Japanese mermaids, we have something a little less human-like, more beastly, with little in common with the common image of mermaids. They seem to possess features that could perhaps be more keeping with some sort of primate that has taken an evolutionary route to the sea. I can’t imagine how a half human half fish could ever come about, but I can entertain the thought of some creature perhaps breaking off from primates long ago and developing adaptations for a more aquatic or at least semi aquatic life. An aquatic creature with grasping hands, for instance, would have a good way of picking up shellfish or crabs, or for reaching into prey hiding places. I don’t think they would resemble humans at all, but maybe something akin to the traditional Japanese mermaids.

I wonder if any of the stories could even be of some sort of odd looking or long finned seal that was perceived as something more humanoid.

So classic mermaids do not strike me as a likely candidate for being a real organism, and as a person in the field of biology, I too am loathe to even venture into the territory of paranormal explanations. But in the case of the small, monkey-like Japanese mermaids, I do find myself speculating about what kind of creature, if any, could have been behind these stories.

Anyway, thanks for your insights and hope you enjoyed the piece.

Mermaids have always fascinated me because they are such an oddity and so out of place with a lot of other cryptids. BF and Nessie at least have some sort of parallel creature to latch onto for an evolution, but mermaids are such an abstract in the animal world. They are literally the combination of two separate animal forms…a chimera really…and one that does not even remotely fit in with our present zoological database.

It is interesting but many moons ago I read a sci-fi story about a russian scientist who experimented on people and animals, creating all manner of crossover things, and yes, he also created a merman. To my mind, unless there was some sort of evolutionary glitch where humans moved back to sea after being on land, I can’t get my head around mermaids (unless you go off into the paranormal, which I’m not ready to settle on). Human characteristics such as human faces and limbs or even hair are not physical characteristics that would have a lot of relevance for adaptation to sea life (except maybe the arms…crabs have their claws).

While I would say mermaids are on the cryptid list of the most “out there” I still can’t quite let it go because there is a record of sightings going on–And no I do not buy the bilge about sailors just being out to sea for too long and putting a pretty face on a dugong just to remind them of their women…it’s as nutty as mermaids.

While I wouldn’t put my money on the existence of mermaids, it is one of those topics I am always eager for information, and new good info about. So THANKS for the posts!!!

I tell you, this article could have been even longer. The history and bizarre cases surrounding these Japanese mermaids are rich and fascinating.

I really liked your analogy of reality television. That is a good observation and I suppose one could see these FeeJee mermaids and other such curiosities as appealing to precisely the same part of us that craves seeing these reality programs. I suppose in every age, we have shared these same innate interests and it is only the mediums for satisfying these that have changed. I suppose the human craving for mystery and something beyond what we know always has, and always will be with us. It really makes one think.

I’d like to say, if one of those Steller’s sea apes pops up someday in a collection, then fake or not, I want to get a look at it.

Anyway, once again I am glad you enjoyed this. Please make sure you read Part 1 of this FeeJee mermaid article if you haven’t already! It goes into the back story behind the rise in these curios.

Thanks again!