Which animal have dual sex?

The term "dual sex" is not a standard biological term. It's possible you're referring to animals that are hermaphrodites.

Hermaphrodites have both male and female reproductive organs. There are many species of animals that exhibit hermaphroditism, including:

* Snails: Many snail species are hermaphrodites and can fertilize their own eggs.

* Earthworms: Earthworms are also hermaphrodites, but they typically cross-fertilize with another worm.

* Some fish: Certain fish species, like clownfish and wrasses, can change sex during their lifetime.

* Some plants: Most flowering plants have both male and female reproductive parts within a single flower.

It's important to remember that the term "dual sex" is not scientifically accurate. It's better to use the term hermaphroditism when discussing animals with both male and female reproductive organs.