The Secret Language of Ships

What's so bad about shellfish and microorganisms hitching a ride? The crusting of barnacles, mussels, and bacteria—called biofouling—creates drag, slowing ships and upping their fuel intake by as much as 40 percent. Foreign species can also invade ecosystems and outcompete native species for food and space. To remove the hitchhikers, the ship goes into dry dock for scraping or power washing.

More than 70 percent of the world's commercial ships sail under what's called a "flag of convenience." This means that the ship is registered in a foreign country and sails under that country's flag, usually to reduce operating costs, sidestep taxes, or avoid the stricter safety standards of the owner's country.