Translated from Sore de Honto?
Of all the bakemono and yokai in Japan, the kappa is the best-known. Depending on the area, they might be known as “gataro” or “kawako” or “gawappa.” This just shows how wide-spread they are. As for appearance, the most stereotypical kappa can be recognized by the indented bowl on his head and by webbed hands and feet.
There are many people who claim to have seen this kind of kappa. But if you research exactly what people describe, it seems like what they are actually seeing is an otter.
Otters come from the mink family, and have a large tail. They can use this tail for support to stand straight up on the river banks. When they do this, they are almost exactly the same size as a human child.
An otter’s skull is soft, and can be flattened out at the top. Just imagine coming upon an otter in the dim evening light, standing upright on a river bank. Water running off its fur, the head flattened out and eyes moving around restlessly, standing at the same height as a human child. Don’t you think it might look just like a kappa?
In the Edo period, if you examine all of the different portraits of kappa, you can see the influence of the otter’s shape. For example, the picture called “Suiko, scroll #20” is obviously a mix between an otter and a turtle.
The distribution of otters in Japan and stories of kappa coincide, from Hokkaido down to Amami island. But nowadays, otters are almost extinct in Japan. I wonder if the legend of the kappa will fade along with them?
百物語怪談会 Hyakumonogatari Kaidankai 
May 03, 2016 @ 11:42:35
The otter idea is interesting. It sounds more likely to me, if indeed Kappa have any basis in reality, than the extremely rare giant amphibian that a television personality has proposed.