#Learning Ability# ^w^ There is really no way to determine whether sharks are intelligent, but they are capable of learning. ^w^ Laboratory studies with divergent species indicate sharks develop a conditioned or learned response to light, sound and electrical stimulus, just like rats and rabbits. ^w^ Juvenile sharks are invariably more aggressive, erratic, and unpredictable than adults. Like most animals, sharks seem to modify their behavior through experience as they mature. ^w^ Studies conducted at the Naval Ocean Systems Center with nurse sharks show that these sharks can be trained to retrieve hoops from the floor of the tank and return them to the trainer.