April 30th, 2013 (Tia Ghose). Shark embryos cannibalize their littermates in the womb, with the largest embryo eating all but one of its siblings.
Now, researchers know why : It’s part of a struggle for paternity in utero, where babies of different fathers compete to be born.
The researchers, who detailed their findings today (April 30) in the journal Biology Letters, analyzed shark embryos found in sand tiger sharks (Carcharias taurus) at various stages of gestation and found that the later in pregnancy, the more likely the remaining shark embryos had just one father.
That finding suggests the cannibalism seen in these embryos is a competitive strategy by which males try to ensure their paternity.
“In some species, the struggle for paternity continues beyond the point where the female [mates with] the male,” said study co-author Demian Chapman, a marine biologist at Stony Brook University of…