Adult sharks have highly sensitive receptors that can detect electric fields emitted by potential prey and predators. And now it turns out that at least in one species, their unborn offspring do too.

“It’s the equivalent of a baby inside a mother responding to external stimuli before it’s born,” said Ryan Kempster, a marine neuroecologist from the University of Western Australia, who along with colleagues reported the findings in the journal PLoS One.

The team studied the eggs of brownbanded bamboo sharks in an aquarium. To record the embryo activity, they scraped off the external layer, allowing them to view the transparent inner layer of the egg case when it was held in front of fiber-optic light.

Embryos that had completed about 90 percent of their physical development — meaning they still had about one to two months remaining in their egg cases — were able to use electrical receptors to detect the signals of predators.