Tswum wondered: why quavers? quaver...

Thanks for bringing up the names of notes, since it has reminded me of something that bugged me for the longest time when I was learning music, and I'd like your opinions, both informed and uninformed.

The names of notes in English in descending order according to note-value are:
Semibreve (whole note)
Minim (half-note)
Crotchet (quarter-note)
Quaver (1/8)
Semiquaver (1/16)
Demisemiquaver (1/32)
Hemidemisemiquaver (1/64)

The names of the same notes in Spanish are:
Redonda (whole note, it means "round")
Blanca (half-note, it means "white")
Negra (quarter-note, it means "black")
Corchea (1/8)
Semicorchea (1/16)
Fusa (1/32)
Semifusa (1/64)

(Since it is so seldom used, I have left out the Breve, that semibreve that looks like it's in jail. Also, I confess, I have forgotten the Spanish name for it, if I was ever taught it )

It always appeared to me that there must be some kind of etymological connection between the terms "crotchet" and "corchea", and I cannot imagine how one came to refer to quarter-notes and the other to eighth-notes. Anyone have any ideas about this?

Also, where did the "fusa/semifusa" words come from? It seems unfair that Spanish musicians are deprived of the fun of endlessly splitting quavers into ever-smaller units with ever-longer denominations!