Maybe something like:

#----------------------------------------
package Zoo::Animal;
use strict;
1;
sub new {
  my $class = shift;
  my $sref_oid = Zoo::Zoo->_gen_oid();
  my $self = { _oid => $$sref_oid, @_ };
  bless $self, $class;
  print "Animal initialised\n";
  return $self;
}
#----------------------------------------
package Zoo::Camel;
use strict;
use base qw( Zoo::Animal );
sub new {
    my ( $class ) = @_;
    my $self = $class->SUPER::new(
      _type  => 'camel',
      _color => 'grey',
      _legs  => 4,
      _humps => 2,
    );
    print "Camel initialised\n";
    return $self;
}
#----------------------------------------
package Zoo::Lama;
use strict;
use base qw( Zoo::Animal );
sub new {
    my ( $class ) = @_;
    my $self = $class->SUPER::new(
      _type  => 'lama',
      _color => 'white',
      _legs  => 4,
    );
    print "Lama initialised\n";
    return $self;
}
[download]

I don't know if I agree with your Zoo::Zoo 8-)

package Zoo::Zoo;

use UUID;
use lib '.';
use base qw( Zoo::Animal Zoo::Camel Zoo::Lama );
[download]

This seems to say to me that a Zoo::Zoo is an Animal, a Camel or a Lama - I would have thought the Zoo is more like a container of Animals, rather than an actual beastie?