Why do the Kage's have animals in the background?


I think the animals are supposed to represent some kind of virtue, but I'm not
sure what.  
Is there any explanation on why those specific animals were chosen?

![Hokage](https://i.stack.imgur.com/xI1Kl.jpg)
![Raikage](https://i.stack.imgur.com/7L1PX.jpg)
![Mizukage](https://i.stack.imgur.com/fuD09.jpg)
![Kazekage](https://i.stack.imgur.com/nwwIn.jpg)




I stumbled across this on a
[forum](http://narutobase.net/forums/showthread.php?t=353407).. I could find
no other references but for the most part, it makes sense somewhat.

>   1. Gaara is the young buffalo with keen instincts and promise.
>
>   2. Tsunade is the rampant moose that charges without hesitation.
>
>   3. Raikage is the bear that holds dominance and power on top of everyone.
>
>   4. Mei is the whale that protects the sea (her village)
>
>   5. Tsuchikage is the ancient scripture, the scripture that possesses much
> knowledge and experience.
>
>




I stumbled across this on a
[forum](http://narutobase.net/forums/showthread.php?t=353407).. I could find
no other references but for the most part, it makes sense somewhat.

>   1. Gaara is the young buffalo with keen instincts and promise.
>
>   2. Tsunade is the rampant moose that charges without hesitation.
>
>   3. Raikage is the bear that holds dominance and power on top of everyone.
>
>   4. Mei is the whale that protects the sea (her village)
>
>   5. Tsuchikage is the ancient scripture, the scripture that possesses much
> knowledge and experience.
>
>

