The Loh Down On Science

You won't believe what sand-tiger-shark embryos eat!

Chapman et al., Proc. Royal Soc. B, 2013.

Top: Sand-tiger-shark embryo (E) and hatchling (H). Bottom: Litter of embryos.

Think your family is dysfunctional? Wait 'til you meet … The Sand Tigers!

This is Sandra Tsing Loh with the Loh Down on Science.

Sand tiger sharks, found worldwide, bring infighting to a new level.  A pregnant mom has a full house of happy embryos.  But it gets ugly fast.  The first embryo to reach a certain size craves a family dinner—literally! It devours its ten or so siblings!  This way, only the fastest-growing shark survives.  Why can’t everyone just get along?!

Demian Chapman from Stony Brook University also wondered that.  So he conducted paternity tests on the embryos of fifteen females before the fishy Hunger Games.  Turned out, most litters were mixes of offspring from different fathers.  And in the dog-eat-dog world of tiger sharks?  The genetic differences made them enemies.  Let the Baby Battles begin!

It seems womb warfare is just male–male competition among dads, taken one step farther.  In fact, it could make life easier for mom by simplifying mate selection.  Hook up with many, give birth to the best. 

And you thought preschool was scary!

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The Loh Down on Science is produced by LDOS Media Lab, with 89.3 KPCC. And made possible by the generous support of the Gordon and Betty Moore Foundation.

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