How do sharks sense tiny electrical signals from prey?

Sharks have a network of jelly-filled sensory canals around the snout called ampullae of Lorenzini. The pores connect to receptors that are extremely sensitive to small electric fields produced by muscle and nerve activity in other animals. This lets sharks track prey even when vision is poor or the target is buried. The system is especially useful for hunting flatfish and other animals hiding on the seafloor. It is one reason sharks are such efficient predators in dim underwater environments.