Embryos Sand Tiger Sharks Devour Their Siblings While in the Womb

While in the in the mothers' wombs, sand tiger sharks embryos fight each other, the largest embryo eating all except on of it siblings, engaging an unexplained cannibalism behavior.  

A recent research suggests that the reason of such cannibalism behavior is the fight for paternity, a kind of natural selection, where babies from different father fight to survive and be born.After a nearly year long of gestation, the mothers sand tiger sharks give birth to two babies sharks of 3.3 feet (1m) long after a , while the Full-grown is about 8.2 feet (2.5 m).

According to the study, the the sand tiger  shark females mate with multiples partners and the cannibalism strategy is an evolutionary strategy wherein the most aggressive male sharks father the ultimately successful baby and thereby out-compete rivals, The Washington Post reported.

To find out, Scientists studied the samples from 15 pregnant females sharks. using the DNA analysis to determine the paternity. "It's exactly the same sort of DNA testing that you might see on Maury Povich to figure out how many dads there are," Chapman underlined. 10 female sharks carried just two embryos, while the rest in early stage of gestation have five to seven embryos.

the females sharks with seven embryos had at least two fathers while females with two embryos most of time had just one one father. possibly the one that grew biggest first tended to devour embryos from other fathers over its full siblings. this can mean that the  loser fathers ultimately provided food for a rival male.