Zoo.pm - A zoo. This has an array that holds many Animal objects. It knows nothing about specific Animal subclasses. It can also have a factory method that creates a new animal and adds it to the zoo collection.
Animal.pm - These are Animal objects. This is a interface type class that merely defines specific methods that Zoo will use. The factory could also logically be here
Animal::Llama - Subclass of Animal that holds Llamas.
Animal::Camel - Subclass of Animal that holds Camels.


This way, a Zoo has a collection (array) of Animals. To get the counts of each animal type, try this:

my %count;
foreach my $animal in (@zooanimals) {
   # $animal is a Animal object.
   my $animal_name = $animal->get_name();
   $count{$animal_name}++;
}
# another loop here to print %count.
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Get it? The Zoo should hold Animals, and know nothing about subtypes of animals.

Exception: - The factory method can know about animal types. That way it can create the appropriate subclass.

sub add_animal() {
   my $type = shift;
   if($type == "Llama") {
      my $newanimal = new Animal::Llama;
   } elsif {$type == "Camel") {
      my $newanimal = new Animal::Camel;
   }
   push (@allanimals, $newanimal);
}

my $zoo = new Zoo;
$zoo->add_animal("Llama");
$zoo->add_animal("Llama");
$zoo->add_animal("Camel");

$zoo->count_animals();

__OUTPUT__
There are 2 Llamas in the zoo.
There are 1 Camels in the zoo.
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This is rough and incomplete. (I would add a Animal::Collection object - a zoo has many collections of animals. A collection is a number of individual animals.) But, this is a better design.
To add a new animal type, you just make two changes - the new class, and add it to the factory method.

Is this clear? I'm happy to clarify if you still need help.