I wonder whether this is due to the fact the verb is used in a very specific sense here.
Analogy is a powerful mechanism of language change which regularizes the conjugation/declension of rare words. Words that are used frequently are relatively immune to analogy because their constant repetition in everyday life reinforces their quirks, whereas rarer irregular words are not worth the effort of memorizing and get “normalized”.
If I remember what Pinker said, it was something like this:
The baseball verb “to fly out” does not come directly from the verb “to fly” but rather from the noun “a fly ball”. Since it passes through a different part of speech it loses its irregularity.
He’s talking about nightjars, also called goatsuckers (including in their nomenclature).
But I’ve not heard that the monster was named after the bird. It seems more that they are both named for goatsucking independently (since the bird supposedly sucks milk whereas the chupacabras supposedly sucks blood.
The bird is a chotacabras, not a chupacabras 
Indeed. If we were, then we’d all be writing like this (by AD Godley, on the introduction of motor buses in Oxford):
WHAT is this that roareth thus?
Can it be a Motor Bus?
Yes, the smell and hideous hum
Indicat Motorem Bum!
Implet in the Corn and High
Terror me Motoris Bi:
Bo Motori clamitabo
Ne Motore caedar a Bo–
Dative be or Ablative
So thou only let us live:
Whither shall thy victims flee?
Spare us, spare us, Motor Be!
Thus I sang; and still anigh
Came in hordes Motores Bi,
Et complebat omne forum
Copia Motorum Borum.
How shall wretches live like us
Cincti Bis Motoribus?
Domine, defende nos
Contra hos Motores Bos!
I suppose that must have come into play when describing multiple varieties or sources of pease (pease already being a bulk noun, not exactly singular). Like fish (singular), fish(plural) and fishes (plural in variety)
I see it in discussions of food , equivalent to beans. It doesn’t seem to be used analogous to fishes.
Thanks you for this: brilliant.
That’s strange then - because ‘pease’ isn’t exactly singular
Because it’s found in Latin America.
Except it was.
I was at at a math training and someone said “formulas”. One of the women there went into complete rant mode about how “formula” is Latin and the correct plural is “formulae” and she could believe how ignorant he was and how dare he teach that word to student and so on for a couple of minutes. Everyone is looking around like, “WTF is going on? What is her problem?” Her attack was vitriolic and everyone felt really sorry for the guy being attacked.
But on rare occasion the Universe is glorious. Later in the training she referred to more than one octopus as “octopi”. I am too much of an ahole to NOT take this opportunity. I turn in my seat to her and clear my throat …
And the plural was peasen.
Teuthology comes up in math class why?
Oh, I’ve been getting that wrong for a while
I would have counter-attacked and told her that she was a pretentious a-hole. That formula had been totally anglicized and it is never wrong to add the plural -s to a borrowed word. Also, if she is going to treat it as a Latin word, does she also use the correct case whenever she uses the word?
I feel strongly about this issue. I cringe when I hear–as I do occasionally–people say phenomenas, medias, etc.
I have one: you have heard of the bikini. But have you seen the monokini? [link blurred to avoid problems with topless models &c]
I doubt it was a misunderstanding, though.
And yet, in the Gospels, it’s “five loaves and two fishes”, presumably the usual sort of plural meaning two specimens of the class.
C’mon, everybody knows fishes is a verb! 
The nox was lit by lux of Luna,
And 'twas a nox most opportuna
To catch a possum or a coona;
For nix was scattered o’er this mundus,
A shallow nix, et non profundus.
On sic a nox with canis unus,
Two boys went out to hunt for coonus…
