Hey my brother, you look tasty!
Cannibalism is the act of any animal consuming members of its own species.
I am particularly fascinated by the siblicide that takes place in the womb of a pregnant sand tiger shark (Carcharias taurus) where even before the pup is born, it is already engaging in cannibalism and the targets are its siblings.
This act is called intrauterine cannibalism, where the pups begin their compete for survival even before they are officially ‘born”. As sharks seem to have a slightly special case being both fish and mammals, there is this special term “Viviparous” which means these animals lay eggs but develop the embryos inside the mother body leading to live births.
Intrauterine cannibalism is known to take place among carnivorous species such as lamnoid sharks and the fire salamander as well as in some teleost fishes. The case for sand tiger sharks is a little more special as usually two pups will emerge, not because the two acknowledge each other as equals, but because the mother has two uteri to keep them apart.
It was found that the sharks produce up to 25,000 eggs in their lifetime, and about 10-20 gets passed into the ovary duct to be fertilised and packaged in avocado shaped egg cases where they develop and start the race by feeding on one another until the fiercest and the fittest remain. More eggs will be passed from the oviduct to ensure that it does not starve if it finishes eating everything.
The following video might require the viewer to have a strong stomach and best watched when you are not dining.
Cannibalism(Zoology). (n.d.). Retrieved 4 7, 2013, from Wikipedia: http://en.wikipedia.org/wiki/Cannibalism_(zoology)#cite_note-26
Sand Tiger Shark. (n.d.). Retrieved 4 7, 2013, from Wikipedia: http://en.wikipedia.org/wiki/Sand_tiger_shark
SULLIVAN, W. (1982, December 7). IN SHARK WOMB, FETUS ‘CANNIBALIZES’ RIVALS. Retrieved 4 7, 2013, from The New York Times: http://www.nytimes.com/1982/12/07/science/in-shark-womb-fetus-cannibalizes-rivals.html
The Battle of the Shark Pups. (n.d.). Retrieved 4 7, 2013, from Discovery: http://dsc.discovery.com/tv-shows/shark-week/about-this-show/shark-pups.htm