Asexual reproduction in animals occurs through fission, budding, fragmentation, and parthenogenesis. Reproduction may be asexual when one individual produces genetically identical offspring, or sexual when the genetic material from two individuals is combined to produce genetically diverse offspring.

Sexual reproduction may involve fertilization inside the body or in the external environment. A species may have separate sexes or combined sexes; when the sexes are combined they may be expressed at different times in the life cycle.

asexual reproduction — a mechanism that produces offspring that are genetically identical to the parent. budding — a form of asexual reproduction that results from the outgrowth of a part of an organism leading to a separation from the original animal into two individuals. fission — (also, binary fission) a form of asexual reproduction in which an organism splits into two separate organisms or two parts that regenerate the missing portions of the body. sexual reproduction — a form of reproduction in which cells containing genetic material from two individuals combines to produce genetically unique offspring.