Internal fertilization

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Fertilization which takes place inside the female body is called Internal fertilization in animals is done through the following different ways:[1][2][3]

At some point, the growing egg or offspring must be expelled. There are three general ways of doing this:

  • Oviparous organisms, including most insects and reptiles, monotremes, dinosaurs and all birds lay eggs that continue to develop after being laid, and hatch later.[8]
  • Viviparous organisms, including almost all mammals (such as whales, kangaroos and humans) bear their young live. The developing young spend proportionately more time within the female's reproductive tract. The young are later released to survive on their own, with varying amounts of help from the parent (s) on the species.[9]

Most species of land animals reproduce by internal fertilization. For example: All reptiles, such as the snake and turtle reproduce by internal fertilization. Males and females usually have an opening called the cloaca through which semen, urine and feces can be released. During mating, the male and female join their cloacas. The male releases semen into the female's cloaca. The spermatozoa then travel up a canal to reach the ova.

See also[edit]


  1. ^ Reichard, U.H. (2002). "Monogamy—A variable relationship" (PDF). Max Planck Research 3: 62–7. Retrieved 24 April 2013. 
  2. ^ Lipton, Judith Eve; Barash, David P. (2001). The Myth of Monogamy: Fidelity and Infidelity in Animals and People. San Francisco: W.H. Freeman and Company. ISBN 0-7167-4004-4. 
  3. ^ Research conducted by Patricia Adair Gowaty. Reported by Morell, V. (1998). "Evolution of sex: A new look at monogamy". Science 281 (5385): 1982–1983. doi:10.1126/science.281.5385.1982. PMID 9767050. 
  4. ^ Diamond, Jared (1991). The Rise and Fall of the Third Chimpanzee. Radius. pp. 360 pages. ISBN 0091742684. 
  5. ^ Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 396–399. ISBN 0-03-910284-X. 
  6. ^ Nina Wedell, Tom Tregenza & Leigh W. Simmons (2008), "Nuptial gifts fail to resolve a sexual conflict in an insect", BMC Evolutionary Biology 8: 204, doi:10.1186/1471-2148-8-204, PMC 2491630, PMID 18627603 
  7. ^ Peter D. Sozou & Robert M. Seymour (2005), "Costly but worthless gifts facilitate courtship", Proceedings of the Royal Society B 272 (1575): 1877–1884, doi:10.1098/rspb.2005.3152, PMC 1559891, PMID 16191592 
  8. ^ Thierry Lodé (2001). Les stratégies de reproduction des animaux (Reproduction Strategies in Animal Kingdom). Eds. Dunod Sciences. Paris.
  9. ^ Blackburn, D. G. (2000). Classification of the reproductive patterns of amniotes.:" Herpetological Monographs", 371-377.
  10. ^ Carrier, J.C.; Musick, J.A.; Heithaus, M.R., ed. (2012). Biology of Sharks and Their Relatives. CRC Press. pp. 296–301. ISBN 1439839247.