Another thing to consider:

The Grimm brothers lived in the late 18th, early 19th century (1785-1863/1786-1859), i.e. about 200 years ago.

And some of the stories the two collected are probably a bit older than that.

Could the German name for a guinea pig have changed from Meerhäschen to Meerschweinchen since then?
At the moment I do not know where to find a dictionary of German at that time...

MudGuard

PS: Mr. Red, I will have a look at your page tonight.