Show I II I Submarine Submarino Principle I First Used by Caddis Fly FlyThe FlyThe I The submarine principle was wasI I used millions of years ago ngo by an on insect known ns as the caddis fly The young of certain caddis flies flics I build a submarine of selected materials found on the bed of a I stream or lake binding th them m together to together to to- gether with silk sUk By Dy attaching or r rj detaching bubbles of air to their j cases and thereby altering the specific gravity the flies flics are able j I to rise or submerge in water i |