Sharks can sense the tiniest of movements — muscles twitching, nerve cells firing. That’s because they can actually sense their prey’s electricity field. (They use electroreceptors, or, as the BBC calls them, “jelly-filled pores on their heads.”) This electric-sensing head-jelly superpower is why it’s so hard to escape a shark. They’re gonna get you. They can feel you out there.
And one type of baby shark — brownbanded bamboo shark embryos still in their egg cases — can also use that sense to escape predators with another power: playing dead. Ed Yong explains at National Geographic:
When they sensed fields that match the breathing of a nearby predator, they quickly froze. They even kept their gills still, effectively holding their breath as long as they could. And they coiled their tail around their bodies in a little still ball.
It’s probably the cutest thing you’ll ever see a shark do, although it’s important to remember that these babies are developing the senses that will turn them into extremely effective killers as adults.