There are many options. You can create an normal array or you can use an list
Code:
animal [] myAnimalArray = new animal[5];
for(int i = 0; i < myAnimalArray.length; i++)
{
   myAnimalArray[i] = new animal();
}//for
Code:
System.Collections.Generic.List<animal> myList = new System.Collections.Generic.List<animal>();
for (int i = 0; i < 5; i++)
{
    myList.Add(new animal());
}//for

int count = myList.Count;