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Fatherless Sharks By: Christian Heinrich
What is Parthenogenesis? • Parthenogenesis is Greek for “virgin birth” • Parthenogenesis has been recorded in many bony animals but never in sharks until 2001 • If sharks really can reproduce with virgin births, that leaves only mammals that cannot reproduce with parthenogenesis • When egg is laid, it fuses with a polar body • Polar body- DNA packed particles that female sharks shed during reproductive cycle • Apomictic parthenogenesis is when the offspring is clone of mother, which is common among plants • Automictic parthenogenesis is when the offspring is half clone of mother • The offspring of the sharks after parthenogenesis is always female since the males are the ones who give the male chromosomes • Sharks are a lot like humans in the way that females are XX and males are XY
All polar bodies are different so the offspring of the sharks are never clones of mother or twins of other offspring • Normally mothers just reabsorb the polar bodies, but in parthenogenesis they fuse with the egg and baffles scientists
First Case of Parthenogenesis • In December 14, 2001, a bonnet head, or type of small hammerhead shark, produced a pup in the Henry Doorly Zoo in Nebraska. • No males were in the tank
Second Case of Parthenogenesis • In 2002, two white- spotted bamboo sharks were born at the Belle Isle Aquarium in Detroit • Mother shared aquarium with one other shark which was female • It may have been parthenogenesis, but it is also a possibility that it can be a hermaphrodite, or containing both male and female sex organs, and also capable of fertilizing it’s own eggs, although this is not confirmed • Another possibility is that the shark could have kept sperm in her body for a long period of time, but it has never been known for a shark to hold sperm for as long as this shark as been away from males • Most animals lay eggs even when they are not fertile, in this case, the eggs would be found and discarded • These eggs were left undisturbed and hatched 15 weeks later
Third Case of Parthenogenesis • In October 10, 2008, Hungarian Aquarium had a confirmed case of parthenogenesis after lone female produced pup • Atlantic Black Tip Shark had a pup with no male genetic information
References • Hirshon, Bob, narr. "Fatherless Sharks." Science Net links. AAAS, 2011. web. 12 Dec 2011. <https://sciencenetlinks.com/science-news/science-updates/fatherless-sharks>. • . "Parthenogenesis." Wikipedia. N.p., 12 Dec 2011. Web. 18 Dec 2011. <https://en.wikipedia.org/wiki/Parthenogenesis
References • Holtcamp, Wendee. "Parthenogenesis in Sharks." Bioscience 59. 59.7 (2009): 1-3. Web. 19 Dec. 2011. <http://www.wendeeholtcamp.com/Sharks/VirginBirthBioscience.pdf>.