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The three traditional modes of reproduction are: [1] Oviparity, taken to be the ancestral condition, where either unfertilised oocytes or fertilised eggs are spawned. [1] Viviparity, including any mechanism where young are born live, or where the development of the young is supported by either parent in or on any part of their body. [1]
They have one opening for excretion and reproduction called the cloaca. They hold the eggs internally for several weeks, providing nutrients, and then lay them and cover them like birds . Like marsupial " joeys ", monotreme " puggles " are larval and fetus-like, [ 9 ] as like them they cannot expand their torso due to the presence of epipubic ...
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In biology, a biological life cycle (or just life cycle when the biological context is clear) is a series of stages of the life of an organism, that begins as a zygote, often in an egg, and concludes as an adult that reproduces, producing an offspring in the form of a new zygote which then itself goes through the same series of stages, the ...
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ ˌ æ n ɪ ˈ m eɪ l i ə / [4]).With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
This type of reproduction has been induced artificially in animal species that naturally reproduce through sex, including fish, amphibians, and mice. Normal egg cells form in the process of meiosis and are haploid , with half as many chromosomes as their mother's body cells.
The maintenance of sexual reproduction (specifically, of its dioecious form) by natural selection in a highly competitive world has long been one of the major mysteries of biology, since both other known mechanisms of reproduction – asexual reproduction and hermaphroditism – possess apparent advantages over it
In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. Fertilization is the fusion of two gametes . [ 1 ] Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization . [ 2 ]