my %bighash = (

 'Arizona'=> {
              'ZOO_1' => [ '5','HIPPO1', ['feat1'],['feat2']],
              'ZOO_2' => [ '10','HIPPO2',['feat1'],['feat2']],
              'ZOO_3' => [ '2', 'PUMA1', ['feat1'],['feat2']],
              'ZOO_5' => [ '13', 'PUMA2',['feat1'],['feat2']],
            },
'Indiana' => {
              'ZOO_2' => [ '10','HIPPO3',  ['feat1'],['feat2']],
              'ZOO_9' => [ '25','ZEBRA1',  ['feat1'],['feat2']],
              'ZOO_5' => [ '13','MONKEY1', ['feat1'],['feat2']],
              'ZOO_6' => [ '23','ZEBRA2',  ['feat1'],['feat2']],
              'ZOO_3' => [ '2', 'PUMA3',   ['feat1'],['feat2']],
              'ZOO_5' => [ '1', 'PUMA4',   ['feat1'],['feat2']],
             },
'Nevada' => {
             'ZOO_3' => [ '3', 'HIPPO4',  ['feat1'],['feat2']], 
             'ZOO_7' => [ '11', 'HIPPO5', ['feat1'],['feat2']], 
             'ZOO_4' => [ '21', 'LION1',  ['feat1'],['feat2']], 
             'ZOO_12' => [ '13','MONKEY2',['feat1'],['feat2']],
         },
      );

##</code><code>##

my %animals;
my @zoos;
foreach my $state (keys %bighash) 
{
   
   foreach my $zoo (keys %{$bighash{$state}}) 
   {    
        foreach my $state2 (keys %bighash) 
        {
            foreach my $zoo2 (keys %{$bighash{$state2}}) 
            {
                my $animal1 = $bighash{$state}{$zoo}[1];
                my $animal2 = $bighash{$state2}{$zoo2}[1];

                if ( is_variation($animal1,$animal2) == 1 )
                {
                    #print "$animal1 - $animal2\n";
                    push @zoos, $zoo;
                }
                push @{$animals{$animal1}{$state}}, [@zoos];
            }
       }
   }
}
print Dumper \%animals ;

sub is_variation
{
    #Test if two animals are variation of others:
    #e.g. HIPPO1 - HIPPO2 -> True 
    #     HIPPO1 - MONKEY2 -> False 

    my	($s1,$s2)	= @_;
    my  ($t1,$t2);
    $s1 =~ /([A-Za-z]+)(\d+)$/;
    $t1 = $1; 
    $s2 =~ /([A-Za-z]+)(\d+)$/;
    $t2 = $1; 

    #print "$t1-$t2\n";
    if ( $t1 eq $t2 )
    {
        return 1;
    }
	return 0;
}	

##</code><code>##

__END__
$VAR1 = {
          'HIPPO1' => { 
                        'Arizona'=> ['ZOO_1', 'ZOO_2'], 
                        # from Zoo1_1 HIPPO1 and Zoo_2 HIPPO2

                        'Indiana'=> ['ZOO_2'],
                        'Nevada' => ['ZOO_3', 'ZOO_7'],
                      }
           # So the hash above contain list of States and
           # Zoos that own variations of Hippo (HIPPO1..5)

           # Same thing apply for animals below:

          'HIPPO2' => { 
                        'Arizona'=> ['ZOO_1', 'ZOO_2'],
                        'Indiana'=> ['ZOO_2'],
                        'Nevada' => ['ZOO_3', 'ZOO_7'],
                      }
          'HIPPO3' => { 
                        'Arizona'=> ['ZOO_1', 'ZOO_2'],
                        'Indiana'=> ['ZOO_2'],
                        'Nevada' => ['ZOO_3', 'ZOO_7'],
                      }
          'HIPPO4' => { 
                        'Arizona'=> ['ZOO_1', 'ZOO_2'],
                        'Indiana'=> ['ZOO_2'],
                        'Nevada' => ['ZOO_3', 'ZOO_4'],
                      }
          'HIPPO5' => { 
                        'Arizona'=> ['ZOO_1', 'ZOO_2'],
                        'Indiana'=> ['ZOO_2'],
                        'Nevada' => ['ZOO_3', 'ZOO_4'],
                      }
          'PUMA1' => { 
                        'Arizona'=> ['ZOO_3', 'ZOO_5'],
                        'Indiana'=> ['ZOO_3', 'ZOO_5'],
                      }
          'PUMA2' => { 
                        'Arizona'=> ['ZOO_3', 'ZOO_5'],
                        'Indiana'=> ['ZOO_3', 'ZOO_5'],
                      }
          'PUMA3' => { 
                        'Arizona'=> ['ZOO_3', 'ZOO_5'],
                        'Indiana'=> ['ZOO_3', 'ZOO_5'],
                      }
          'PUMA4' => { 
                        'Arizona'=> ['ZOO_3', 'ZOO_5'],
                        'Indiana'=> ['ZOO_3', 'ZOO_5'],
                      }
          'MONKEY1' => { 
                        'Indiana'=> ['ZOO_5'],
                        'Nevada'=> ['ZOO_12'],
                      }
          'MONKEY2' => { 
                        'Indiana'=> ['ZOO_5'],
                        'Nevada'=> ['ZOO_12'],
                      }
          'ZEBRA1' => { 
                        'Indiana'=> ['ZOO_6','ZOO_9'],
                      }
          'ZEBRA2' => { 
                        'Indiana'=> ['ZOO_6','ZOO_9'],
                      }
          'LION1' => { 
                        'Nevada'=> ['ZOO_4'],
                      }
        };