Sharks can sense their prey’s minute electric fields, such as those produced when muscles twitch or nerve cells fire. This super-sense is part of what makes sharks such formidable hunters—you can’t hide from them if the very act of living can give you away.  But the tables are turned when sharks are young. As they begin life, they’re as vulnerable as any other fish, and their electric sense helps them to hide instead of hunt.

The brown-banded bamboo shark lives in the western Pacific, between Japan and Australia. While some sharks give birth to live young, the bamboo shark is one of those that lays eggs. Each embryo is encased inside a pouch called a mermaid’s purse, which