Graphic description of fraction of age cohorts still living.
The shapes of survivorship curves differ for different species. General categories of shapes are classified as , , and curves.
Type II curves are equivalent to exponential decline in population whereas type I curves show biases towards young-age but not old-age . Type III curves, on the other hand, are opposite of type I curves, with biases towards old-age but not young-age survival.
Note that these curves represent 'ideals' rather than rigid categories to which species must conform.
Survivorship curves are generated from that entered into life tables.