How are shark pups born? -- Author's Note
I have this trick that I use with my pregnant friends ever since I wrote this article: If they're concerned about the birthing process, I explain how shark pups are born. The process is so violent from beginning to end that delivering a 9-pound baby suddenly doesn't seem very stressful.
Take, for example, conception. Sharks don't mate in pairs, so male sharks simply bite a female shark to hold her in place while they copulate, and then they disappear. A female shark may carry several dozen embryos or eggs within her uteri, but during gestation, the ones that get teeth first tend to eat the others. And then, after gestation, a period that can last up to two years for some species, mother sharks watch as their new pups swim away as soon as they're born -- perhaps because they're trying to avoid being eaten by their mother.
See what I mean? The next time a pregnant woman is worried about swollen feet or nighttime feedings, just remind her that at least human babies don't practice cannibalism in the womb or swim away from their mothers because they fear she's a predator.
- Australian Marine Conservation Society. "Sharks and Rays." (April 24, 2008) http://www.amcs.org.au/default2.asp?active_page_id=196
- Bartlett, Lawrence. "Saving baby-eating sharks from themselves." Cosmos Magazine. Aug. 25, 2006. (April 22, 2008) http://www.cosmosmagazine.com/node/597
- Bester, Cathleen. "Spiny Dogfish." Florida Museum of Natural History Ichthyology Department. (April 21, 2008) http://www.flmnh.ufl.edu/fish/Gallery/Descript/Spinydogfish/SpinyDogfish.html
- Carrier, Jeffrey C. "Shark." Microsoft Encarta Online Encyclopedia. 2007. (April 24, 2008) http://encarta.msn.com/encyclopedia_761552860_2/shark.html
- Chapman, Demian D., Mahmood S. Shivji, Ed Louis, Julie Sommer, Hugh Fletcher and Paulo A. Prodohl. "Virgin birth in a hammerhead shark." Biology Letters. 2007. (April 22, 2008) http://www.omahazoo.com/ccr/genetics/papers/bonnethead.pdf
- Conrath, Christina L. "Chapter 7: Reproductive Biology." Elasmobranch Fisheries Management Techniques. 2004. (April 25, 2008) http://www.flmnh.ufl.edu/fish/organizations/ssg/EFMT/7.pdf
- Cooper, Pete. "Blue Shark." Florida Museum of Natural History Ichthyology Department. (April 21, 2008) http://www.flmnh.ufl.edu/fish/gallery/descript/blueshark/blueshark.html
- Dingerkus, Guido. "The Shark Watchers' Guide." Wanderer Books. 1985.
- Discovery Channel. "Shark Reproduction." (April 24, 2008) http://www.discoverychannel.com.au/sharks/reproduction/index.shtml
- Greven. H. "Viviparous Sharks." Shark Info. (April 22, 2008) http://www.shark-info.ch/SI1_00e/vivipary.html
- Martin, R. Aidan. "Horn Shark." ReefQuest Centre for Shark Research. (April 22, 2008) http://www.elasmo-research.org/education/ecology/kelp-horn_shark.htm
- Martin, R. Aidan. "Intrauterine Cannibalism in Sharks." ReefQuest Centre for Shark Research. (April 22, 2008) http://www.elasmo-research.org/education/topics/lh_intrauterine_cannibalism.htm
- National Aquarium in Baltimore. "Sand tiger shark." (April 22, 2008) http://www.aqua.org/animals_sandtigershark.html
- National Shark Research Consortium. "Shark Biology." Florida Program for Shark Research - Florida Museum of Natural History. (April 21, 2008) http://www.flmnh.ufl.edu/fish/sharks/nsrc/Biology.htm
- Oregon Coast Aquarium. "Sharks and their Relatives." (April 24, 2008) http://www.aquarium.org/documents/background_shark.pdf
- Pratt, Harold L. Jr. and Jeffrey C. Carrier. "A review of elasmobranch reproductive behavior with a case study on the nurse shark, Ginglymostoma cirratum." Environmental Biology of Fishes. 2001.
- Queen's University Belfast. "No Sex Please, We're Female Sharks." Science Daily. May 23, 2007. (April 21, 2008) http://www.sciencedaily.com/releases/2007/05/070523072254.htm
- Saville, Kenneth J., Andrea M. Lindley et al. "Multiple Paternity in the nurse shark, Ginglymostoma cirratum." Environmental Biology of Fishes. 2002.
- SeaWorld. "Sharks and Rays: Birth and Care of Young." (April 22, 2008) http://www.seaworld.org/animal-info/info-books/sharks-&-rays/birth-&-care.htm
- SeaWorld. "Sharks and Rays: Reproduction." (April 22, 2008) http://www.seaworld.org/animal-info/info-books/sharks-&-rays/reproduction.htm
- Shark Trust. "Baby Sharks." 2007. (April 21, 2008) www.sharktrust.org/do_download.asp?did=27359
- Weiss, Rick. "Australia Hatches Plan to Save Gray Nurse Shark." The Washington Post. March 27, 2006. (April 22, 2008) http://www.washingtonpost.com/wp-dyn/content/article/2006/03/26/AR2006032600601.html