Marine iguanas are among the world's most unusual creatures. Specially adapted to one of the most harsh and unforgiving environments on earth, they live on lava rock beaches in the Galapagos Islands, covering almost every surface that the sun touches as they bask in the heat. There is no food for them on the barren shore and the vegetation inland is coarse and inedible for them. These vegetarian lizards have evolved in order to survive in this world. They live on algae that grows in the raging surf along the coast, sometimes as deep as 33m, or 100 feet below the surface. The iguanas are cold blooded and they rely on the heat of the sun to warm their bodies so they can move swiftly, as well as to allow them to digest food. Warm muscles are crucial to avoid predators like hawks, foxes and large rodents. The black rocks are a perfect place to soak up heat and seek shelter. They lie in the open until they have warmed enough to brave the cool water. Despite being at the equator, these islands are surrounded by cool ocean currents that keep the temperature low. The lizards will have a very limited time once they begin to lose body heat, and they will only feed for approximately 30 to 60 minutes each day, provided they have warmed enough to do so. Once warm, the iguanas begin diving off cliffs or slipping off the rocks into the surf to feed. They leave the shore in groups, timed as if on a synchronized clock. They are powerful swimmers and they can hold their breath for up to 30 minutes at a time. They are limited by the temperature and their feeding is done as quickly as possible before they return to the shore to warm up again so they can digest what they ate. They will enter the water once per day and it is important that they store up as much algae in their bellies as they can in a short time. The algae, and the water that they ingest contain enough salt that most creatures would be unable to survive on this diet. But the lizards have another unique adaptation; special salt ducts that allow them to expel the salt in a thick liquid that is sneezed out of their nostrils. Lying on the rocks after feeding allows them to digest the algae and rid their bodies of the toxic levels of salt. Keeping an eye on the sky above them for birds of prey, they must always be wary. The marine iguanas have short snout and a face that closely resembles a dinosaur. In fact, many people believe that the marine iguanas provided the inspiration for the famous Hollywood monster, Godzilla. Their faces are almost identical. The Galapagos Islands are home to some of the most unusual creatures on the planet and people journey there for a close look at some very unique wildlife. Charles Darwin made these islands famous when he studied the wildlife there in 1835 and put forth his theory of evolution. Swimming with marine iguanas is a highlight for divers from around the world and a big part of the adventure that many seek in the Galapagos.