What's up with animal names ending in る?


猿・ツル・ホタル・カエル

る is a rather uncommon mora in nouns, especially at the end. But there seem to
be an unproportional amount of animal names that end in る.

Is that just a coincidence?

For 猿 at least, there seems to be a theory that it's name is derived from a
verb:

> サルの語源には非常に多くの説があり未詳だが、中でも有力と考えられているのは、獣の中では知恵が勝っていることから「マサル（勝る）」の意味とする説。

-- [語源由来辞典](http://gogen-allguide.com/sa/saru_monkey.html)




Here are a few etymology theories I've bumped into.

  * サル -- Attested in Old Japanese. Not so likely to be from 勝【まさ】る. Might instead be from Ainu _sarush_ or _saro_. _Sar_ or _sara_ means "tail", and _-ush_ is a suffix that means "having". See also [the relevant entries in Batchelor's Ainu dictionary](https://archive.org/details/ainuenglishjapan00batcuoft/page/390/mode/2up). Both [Gogen-Allguide](http://gogen-allguide.com/sa/saru_monkey.html) and [Nihon Jiten](http://www.nihonjiten.com/data/45912.html) suggest a derivation from Chinese 猻 ("monkey"), but they each list the reading as _sar_ , while [the Wiktionary entry](https://en.wiktionary.org/wiki/%E7%8C%BB#Chinese) shows Old Chinese //*suːn//, Middle Chinese //suən//, modern Mandarin _sūn_ and Cantonese _syun¹_ -- no _sar_.
  * ツル -- Attested in Old Japanese. Appears to be a regional word. Compare also Korean 두루미 ( _durumi_ ), Proto-Turkic _*durunja_ (“crane”) (whence Turkish _turna_ ), Mongolian тогоруу ( _togoruu_ , “crane”), Hungarian _daru_ (“crane”). See also [the entry at Wiktionary](https://en.wiktionary.org/wiki/%E9%B6%B4#Japanese).
  * カエル -- Attested in Old Japanese. From Old Japanese form _kaperu_. As Naruto notes, possibly cognate with verbs _kaeru_ ("to return") or _kaeru_ ("to spawn"), both also from older form _kaperu_. See also the Wiktionary entries at [蛙](https://en.wiktionary.org/wiki/%E8%9B%99#Japanese), [帰る](https://en.wiktionary.org/wiki/%E5%B8%B0%E3%82%8B#Japanese), and [孵る](https://en.wiktionary.org/wiki/%E5%AD%B5%E3%82%8B#Japanese).
  * ホタル -- Attested in Old Japanese. Also as Naruto notes, most likely 火【ほ】 (ancient reading only found in compounds) + 垂【た】る ("hanging", the way the bug's sparkle-butt hangs down). Some sources suggest that _-taru_ here might be from 照【て】る, but the vowel shift makes this unlikely. See also the entries at [Nihon Jiten](http://www.nihonjiten.com/data/46573.html) and [Gogen-Allguide](http://gogen-allguide.com/ho/hotaru.html) (both in Japanese).

So only two of these are probably from verb roots.




Here are a few etymology theories I've bumped into.

  * サル -- Attested in Old Japanese. Not so likely to be from 勝【まさ】る. Might instead be from Ainu _sarush_ or _saro_. _Sar_ or _sara_ means "tail", and _-ush_ is a suffix that means "having". See also [the relevant entries in Batchelor's Ainu dictionary](https://archive.org/details/ainuenglishjapan00batcuoft/page/390/mode/2up). Both [Gogen-Allguide](http://gogen-allguide.com/sa/saru_monkey.html) and [Nihon Jiten](http://www.nihonjiten.com/data/45912.html) suggest a derivation from Chinese 猻 ("monkey"), but they each list the reading as _sar_ , while [the Wiktionary entry](https://en.wiktionary.org/wiki/%E7%8C%BB#Chinese) shows Old Chinese //*suːn//, Middle Chinese //suən//, modern Mandarin _sūn_ and Cantonese _syun¹_ -- no _sar_.
  * ツル -- Attested in Old Japanese. Appears to be a regional word. Compare also Korean 두루미 ( _durumi_ ), Proto-Turkic _*durunja_ (“crane”) (whence Turkish _turna_ ), Mongolian тогоруу ( _togoruu_ , “crane”), Hungarian _daru_ (“crane”). See also [the entry at Wiktionary](https://en.wiktionary.org/wiki/%E9%B6%B4#Japanese).
  * カエル -- Attested in Old Japanese. From Old Japanese form _kaperu_. As Naruto notes, possibly cognate with verbs _kaeru_ ("to return") or _kaeru_ ("to spawn"), both also from older form _kaperu_. See also the Wiktionary entries at [蛙](https://en.wiktionary.org/wiki/%E8%9B%99#Japanese), [帰る](https://en.wiktionary.org/wiki/%E5%B8%B0%E3%82%8B#Japanese), and [孵る](https://en.wiktionary.org/wiki/%E5%AD%B5%E3%82%8B#Japanese).
  * ホタル -- Attested in Old Japanese. Also as Naruto notes, most likely 火【ほ】 (ancient reading only found in compounds) + 垂【た】る ("hanging", the way the bug's sparkle-butt hangs down). Some sources suggest that _-taru_ here might be from 照【て】る, but the vowel shift makes this unlikely. See also the entries at [Nihon Jiten](http://www.nihonjiten.com/data/46573.html) and [Gogen-Allguide](http://gogen-allguide.com/ho/hotaru.html) (both in Japanese).

So only two of these are probably from verb roots.

