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Asexual reproduction is found in nearly half of the animal phyla. [57] Parthenogenesis occurs in the hammerhead shark [ 58 ] and the blacktip shark . [ 59 ] [ 60 ] In both cases, the sharks had reached sexual maturity in captivity in the absence of males, and in both cases the offspring were shown to be genetically identical to the mothers.
Since the reproduction is asexual, the newly created organism is a clone and, excepting mutations, is genetically identical to the parent organism. Organisms such as hydra use regenerative cells for reproduction in the process of budding. In hydra, a bud develops as an outgrowth due to repeated cell division at one specific site.
[9] [10] [11] This type of reproduction has been induced artificially in a number of animal species that naturally reproduce through sex, including fish, amphibians, and mice. [12] [13] Some species reproduce exclusively by parthenogenesis (such as the bdelloid rotifers), while others can switch between sexual reproduction and parthenogenesis.
[5] [6] Some of the mechanisms are explored and used in plants and animals are binary fission, budding, fragmentation, and parthenogenesis. [7] It can also occur during some forms of asexual reproduction, when a single parent organism produces genetically identical offspring by itself. [8] [9]
Asexual reproduction in sponges occurs via budding, either by external or internal buds. The internal buds are called gemmules. The internal buds are called gemmules. Only endogenous types of buds develop into new sponges.
Asexual reproduction can proceed by budding, fission, or spore formation and does not involve the union of gametes, which accordingly results in a much faster rate of reproduction compared to sexual reproduction, where 50% of offspring are males and unable to produce offspring themselves.
It is an almost universal attribute of polyps to reproduce asexually by the method of budding. This mode of reproduction may be combined with sexual reproduction, or may be the sole method by which the polyp produces offspring, in which case the polyp is entirely without sexual organs. [1]
Fragmentation in multicellular or colonial organisms is a form of asexual reproduction or cloning, where an organism is split into fragments upon maturation and the split part becomes the new individual. The organism may develop specific organs or zones to shed or be easily broken off.