How do life spans of animals differ?

Each species has an average live span and individuals within each species can have their own life span. For example, according to the CDC the average life expectancy for a human is 77.7 years. Some humans die at birth while others live past 100.

Some species, like flies, have very short life spans, averaging only one day while a Galapagos tortoise could live more than 200 years.

Even within a species there is variation. For example, a large breed dog like an Irish Wolfhound has an average life expectancy of 6.2 years while a small breed dog like a Miniature Poodle has an average life expectancy of 14.8 years.