A survivorship curve is a graph of the percentage of a particular species that is living versus time. This curve can be used to measure the percent of a given population of a particular species that survives at different points during the life cycle. There are three basic types of survivorship curves: Type I, Type II, and Type III. Type I curves show a population that mostly survives in early and middle stages and then shows a rapid dying at the end of the life cycle. Humans follow this type of pattern. Type II curves show a relatively linear drop in survivorship over time. Many small birds follow this type of pattern. Finally, Type III curves show a population that loses most of its population early on and then a smaller percentage live to the end of the life cycle. Species exhibiting this type of curve tend to have a larger number of offspring to try to overcome this early high mortality and continue the species. Frogs and octopi tend to follow this type of pattern. The second reference link below shows an example graph of all three curves.