My dive group has a novel way of collecting octopus when they go on gathering trips. They grab zillions of seashells from the bottom and stuff them in a bag. Back at the boat, they simply spread the shells out on the deck of the boat and let the sun do it's job. within minutes, baby octopuses will emerge, searching for life-giving water.
The octopuses you usually catch in North Carolina to Florida include O. Briareus, O. Vulgaris and O mercatoris, with Briareuses being by far the most common. It's actually pretty hard to get your paws on a vulgaris.