Sailors talk some complete twaddle at the best of times (I live close to HMS Heron) but blaming a six inch fish for delays in deployment or delivery takes some neck!
I love this resource. I'll be hunting down a beast that delays IT systems deployment. Some sort of insect is indicated ...
The difference here is that these little beasties magically make a ship run slowly. I would bet real money that their invention was to cover up late delivery or whatever. Basically, an excuse that no land lubber of the time could possibly refute.
Can east asian beasts be included? If so, I would suggest Qilin (Chinese) or Kirin (Japanese) (yes, the one on the beer label).
"It does not include beasts from non-European sources unless those beasts are the basis of Bestiary, Physiologus, or other Western beast legends."
That's a shame because there is a bit of an overlap throughout history of beasties finding a new home - far away from where they originated, thanks to an enterprising traveller spreading stories in passing.
https://en.wikipedia.org/wiki/Qilin and keep on reading and clicking to lose a few hours!
https://the-toast.net/2015/04/01/two-medieval-monks-invent-b...
There's a cool little animation based on this - https://www.youtube.com/watch?v=57BTS-W_2QI
