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How do monotreme mammals reproduce differently from most other mammals?
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Sequential changes in the position of the child during labour.
Monotremes, such as the platypus and echidnas, differ from most other mammals primarily because they are oviparous, meaning they lay shelled eggs rather than giving birth to live young.1
Their reproductive process involves several distinct features:
- Egg-laying: Unlike placental and marsupial mammals, monotremes produce eggs that are predominantly yolk-filled, similar to those of reptiles and birds.12
- Anatomy: The female reproductive tract in monotremes consists of two oviducts that terminate in shell glands, which empty into a common opening called the cloaca, used for both reproduction and excretion.13
- Development: Young monotremes hatch at a relatively early, altricial stage of development and remain dependent on the parent.2
- Lactation: While they lack the specialized nipples found in other mammals, monotremes still nourish their young with milk secreted by mammary glands.4
In contrast, placental mammals utilize a placenta for internal gestation, while marsupials typically give birth to underdeveloped young that complete their growth within a marsupium or pouch.24