The most common barnacle belongs to the order Balanus. The species Balanus nubilus, found in Puget Sound, can reach a diameter of nearly a foot and is said to be good to eat. Barnacles have existed since Jurassic times, the period in the earth's history during which dinosaurs lived. Fossils more than 150 million years old have revealed the presence of barnacles, whose ancestry can be traced back nearly 400 million years. They argued that, being a fish, the barnacle goose could be eaten.
Barnacles live only in salt water.
However, most barnacles must be fertilized by a neighbor, and that is one reason why they grow in large colonies. If barnacles are allowed to accumulate on a ship's hull, the ship will travel slower in the water, or it will have to burn more fuel to keep up its speed, than it would otherwise. A sixmonth growth of barnacles can result in having to burn 40 to 45 percent more fuel to maintain cruising speed. Although many new ideas have been tested, the best way to keep barnacles from growing on a ship's hull is still to paint the hull with copper bottom paint. In both of these stages of development the barnacles swim about freely, making up part of the mass of microscopic plants and animals collectively called plankton.