[TYPO3] Merging databases

[Goar Sandorff]

Hello,

I created two sites using two different but similar content, let's say "Botany" 
and "Zoology.".  Now I wish to merge both sites into a new one, let's say 
a "Nature" site comprising the content of both.  

Nature
--Botany
----current content
--Zoology
----current content

Both sites have the same structure, template, theme, css, even colors, fonts 
etc.  
Is it possible to merge both databases?
Alternatively...
Is it possible to manage both databases from a single typo3 system, sharing 
a common menu?

Any idea will be appreciated.