The loggerhead turtle has a 10 year migration period in which it circles round the Atlantic Ocean. A study took 79 newly born loggerheads and put them in a circular tank. The tank was surrounded by a big electrical coil and the scientists messed around with it, generating magnetic fields to match those of northern Florida, Portugal and other places on the turtles 10 year circuit. The turtles responded and turned in the direction that they would had they been in migration out in the real world. Nobody is quite sure how the turtles do it, but they detect the magnetic field which surrounds the Earth and grows weaker or stronger depending on where you are.
2 - Infrared Cameras or Thermo-Receptors
The Pit Viper is so called because of a deep pit on either side of its head, just between its eyes and nostrils. These pits are sensitive to infrared radiation to help it find and catch smaller prey. Having two pits allows stereo vision, enabling the snake to determine distance and direction, similar to how infrared cameras work. Experiments have shown that in pitch black, and without the sense of smell, the pit viper can strike accurately at moving objects that are less than 0.2°C warmer than the background temperature.
Other animals with this ability, though not as good as the Pit Viper, are rattlesnakes, boas, vampire bats and some butterflies.
3 - Echolocation and Ultrasound
Echolocation is very similar to SONAR (SOund Navigation And Ranging) where a sound is produced, usually an ultrasound (very high frequency) and the time measured for the sound to bounce back or echo is used to calculate how far away objects are from the source. Several animals have this ability, most notably the bat which uses it to navigate in the almost pitch black caves where it lives and to catch insects into the night. Typically bats call out at a frequency of 14,000 Hz to well beyond 100,000 Hz and can be identified by their frequency. Bat detecting machines are used to record the ultrasounds, since they are virutally all outside human hearing range, and databases or libraries of typical calls have been collected so that specialists can identify specific bat species for whatever reasons.
Whales, dolphins, porpoises and orcas use a similar method, emitting a focused beam of high-frequency clicks. The only known mammals (other than below) to use echolocation are shrews and tenrecs (very similar to the shrew) which emit a series of ultrasonic squeaks. Although unlike bats they use it to investigate their habitat rather than finding food.
Human echolocation has also been known to occur in humans, though only ever in blind people. One remarkable case is of Daniel Kish who clicks his tongue and listens to the echo. Although completely blind, he is able to ride a bike and hike in unknown wilderness. He teaches his echolocation method to other blind people. Ben Underwood, a young, blind boy, discovered echolocation at the age of five. He is able to detect the position, size and composition of objects near him, and sometimes their shape, also by clicking his tongue. As such he is able to run, play basketball, skateboard and rollerblade.