Also sex determination does not apply to simultaneous hermaphrodites (except in species with mix mating systems).
[6] It is known that simultaneous hermaphroditism that exclusively reproduces through self-fertilization has evolved many times in plants and animals, but it might not last long evolutionarily.
[8] This model explains simultaneous hermaphroditism as a reproductive adaptation to limited mating opportunities.
The low density model is helpful for understanding the development of simultaneous hermaphroditism in many animal species.
For example, in crustaceans simultaneous hermaphroditism can be found in groups that are sessile or live in environments with limited mating opportunities.