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The biologist Thierry Lodé proposed (2001, 2012) five modes of reproduction based on the relationship between the zygote (fertilised egg) and the parents: [1] [2]. Ovuliparity: fertilisation is external, the oocytes being released into the environment and fertilised outside the body by the male. [1]
The specific problem is: due to unclear definitions for fertility, fecundity and derivative terms depending on whether the term is being used in demography, epidemiology or clinical medicine. For example fecundity is the potential to for a female to become pregnant and carry that pregnancy to a live birth in demography, while in clinical ...
Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization. [2] Mating may also lead to external fertilization, as seen in amphibians, fishes and plants. For most species, mating is between two individuals of opposite sexes.
Animals, including mammals, produce gametes (sperm and egg) through meiosis in gonads (testicles in males and ovaries in females). Sperm are produced by the process of spermatogenesis and eggs are produced by oogenesis. These processes are outlined in the article gametogenesis.
Examples include the oviparous sharks, such as the horn shark, and oviparous rays, such as skates. In these cases, the male is equipped with a pair of modified pelvic fins known as claspers. Marine fish can produce high numbers of eggs which are often released into the open water column. The eggs have an average diameter of 1 millimetre (0.039 in).
The foal was only a few hours old when her rescuer pulled her out of the icy stream in Kosciuszko National Park in New South Wales, Australia. The district is known for its alpine sports and rocky ...
Parthenogenesis is a mode of asexual reproduction in which offspring are produced by females without the genetic contribution of a male. Among all the sexual vertebrates, the only examples of true parthenogenesis, in which all-female populations reproduce without the involvement of males, are found in squamate reptiles (snakes and lizards). [1]
Image credits: BlueberrySympathizer There is an epidemic of animals in need of new homes. While there have (arguably) been some improvements in the situation over the years, things are still dire.