The mammalian class is among the most developed and diverse groups of living creatures on Earth. It includes species ranging in size from just 2 grams to as much as 180 tons, from egg-laying mammals to those that give birth to live young. Members of this class inhabit nearly all geographical regions and habitats across the planet. Observing a mammal in its natural environment is a unique experience that can captivate you for many hours. Sadly, in most parts of the world, it has already become very difficult to see mammals in the wild.