These cannibal baby sharks eat their siblings in the womb – and sketches show just how gruesome it can be

As adults, sand tiger sharks are known for being relatively non-aggressive. But as babies, these animals engage in a cannibalistic war with dozens of siblings in which only one survives. 

It's all part of a natural occurrence known as intrauterine cannibalism. Sand tiger sharks are perhaps one of the most well-known species in which this occurs. These sharks are ovoviviparous, meaning that their offspring grow in eggs in the sharks' uteri until they hatch, at which point, they emerge into the ocean. 

"It is survival of the fittest. The strongest one will emerge," Lizeth Webster, curator of fish and invertebrates at the Long Island Aquarium in New York told CBS News. "The healthiest one will absorb all of the nutrients, not leaving enough for the others, so it will consume others in the womb."