When it comes to sailing the seas, the compass is one of man's greatest inventions. That's why researchers were surprised to discover that some bacteria have tiny, built in compasses. But these compasses are simple affairs based on tiny bits of iron within the bacteria. Now it has been discovered that loggerhead turtles not only have a built in compass, but also use it to pinpoint their location.
Depending on position, the Earth's magnetic field encounters the Earth's surface at differing angles. Using very sophisticated equipment, we can measure these angles and determine longitude and latitude. Young loggerhead turtles must stay within the ocean current system that surrounds the Sargasso Sea in the center of the Atlantic. When they get so far north in this current system that they might leave it, they turn south and return to a more central location within the system. When they get too far south, they turn north. To see if the turtles could actually sense their location based on magnetic fields, researchers tested loggerheads in tanks surrounded by electric coils. When they simulated magnetic conditions on the northern end of the turtles' boundary, the turtles swam south. When they simulated magnetic conditions at the southern boundary, the turtles swam north.
If the loggerheads' navigation system evolved slowly over millions of years, it would have been of no survival value to the turtles until it was complete. Since the turtles would have a very low survival rate without it, their navigation system bears witness to the all-wise, powerful Creator Who made all things.