Mermaid Tails

Q: I’ve noticed that while mermaid[1] tails are depicted as fish-like, their swimming motion is up and down like a dolphin’s instead of side to side like a fish. Why is this?

A: One may think of a mermaid as:

  1. A woman with a fish’s tail instead of legs[2]
  2. A fish with a woman’s head, arms, and torso

In other words there are two halves and the human half influences the piscine half just as much as the piscine half influences the human half.

The human half gains the ability to live and breathe[3] underwater while the piscine half gains the ability to swim like all mammals that live in the ocean. The mermaid’s tail is more flexible and proportionally longer than that of many fish[4]. There are also many different ways to depict a mermaid’s tail, but that is beyond the scope of this FAQ.

One could simply say “it’s the way mermaid tails have always been depicted” and let the discussion rest. No matter how much we may wish otherwise, mermaids don’t exist. Therefore, almost any depiction is correct. Nonetheless, there does seem to be a certain convention followed when artists are depicting mermaids.

Mermaid Tails with fins as small as these won't provide much in the way of propulsion.

Tailfins as small as these won’t provide much in the way of propulsion.

With regard to Urban Mermaid and the entire series, Tails from Colony Island, the author envisions a ‘clean’ look. This means no pelvic fins, no dorsal fins, and no fin-skirts like Ariel and her family. Scale colouration is within a certain range of greens, grays, and silvers[5]. There are no long, curly wurly tails and no extravagant tail fins.

There are also no knee joints. This is the author’s personal preference. While it is common for artists to depict mermaid tails with ‘knees’, the author feels that it starts to look like someone in a costume. A ‘knee-less’ tail has a more flowing look to it and in the case of mermaids, more feminine as well,

The prologue to Urban Mermaid describes how Poseidon and his son, Triton, conceived of mermaids as having a variety of traits found in other marine life as well as a few attributes necessary to life on land. While it is not explicitly stated[6] in the prologue, it is implied that Poseidon is rather fond of dolphins. He apparently chose for mermaid tails[7] to mimic the morphology and swimming abilities of a dolphin whilst retaining the scales of a fish.

Like all animals, there are variations in tail length, and fin shape, as well as where the tail actually begins. For some mermaids, the scale line begins below the hips while for others, it’s closer to the waist. The curve of the mermaid’s buttocks are visible beneath her scales. The bikini area is faintly visible as well. The tail’s real flexibility begins seven to eight inches below this point.

Male and female genitalia are both internal and form part of the cloaca. The cloaca is guarded by two narrow, muscular ridges and are part of a slightly darker medial line of scales on the ventral side. This medial line ends around 12 to 16 inches below the cloaca. The scale colouration lightens until it becomes indistinguishable from the rest of the mermaid’s scales. Thus, the opening to the cloaca  is difficult to discern and is therefore hidden by a kind of protective camouflage.

Finally, it should be noted that as his series progresses, the author will refine his vision of how mermaids should look. Therefore, measurements, proportions, etc. are subject to minor modifications.

For a look at how various artists have interpreted the idea of mermaid tails, check out the author’s Pintrist boards:


The preceding discourse concerns is how the author envisions the merfolk of Colony Island would appear and behave. His opinions and prejudices are just that; opinions and prejudices. They are not intended to defame or belittle the vision of any reader, writer, or illustrator. Sadly, there are no merfolk around to prove or disprove our ideas and speculation.


[1] This discussion applies to mermen as well as mermaids.

[2] There have been many different ideas as to how the tail should look and where it should begin. One vision has the tail as two scale-covered legs with a fin at the end of each instead of a foot.

[3] Just how a mermaid breathes under water will be discussed in another FAQ.

[4] In many respects, it is almost eel-like in flexibility.

[5] Mermaids known as ‘gingers’ have a reddish-orange scale colouration. There is a more narrow range of colour variations than that of their green-tail cousins.

[6] It was necessary to keep the page-count down as well as avoiding an overly excruciating level of detail.

[7] A mermaid’s tail, not including the fin, is just over two to three feet longer than her legs. The main part of the tail fin itself is one foot long. A mermaid’s tail is flexible enough to curl around her like a cat’s and allows her to brush her own back or that of her mate with her tail fin. The touch of a tail fin – whether it is her own or her mate’s – on a mermaid’s back has a soothing effect.


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