Many birds, especially those that migrate, can use the "Earth's magnetic field to stay their course during long flights. Scientists still aren't sure how they do it, but one recent study suggests birds might have a form of synesthesia that lets them "see" the planet's magnetic lines as patterns of color or light that is overlaid on their visual surroundings. Humans must rely on familiar landmarks or the sun's position to locate North, and many can't even manage that.
Drum Fish
Some fish like this drum fish "hear" using their air bladders. The bladders detect sound vibrations and relay them to the inner ear via a set of bones in the middle ear called the "Weberian apparatus." Hair cells in the inner ear respond to the vibrations and transmit the sound information to the fish's brain.
Rats
Most rats have poor vision, but they make up for it with the "whiskers on their snouts. They use the long hairs, also called "vibrissae," in the same way that blind people use canes. By whisking the hairs across objects the come across, rats and other rodents form mental pictures of their surroundings.
Moths
For moths, the term "love is in the air" is something to be taken literally. The furry insects can detect chemical love signals, called "pheromones," emitted by the opposite sex from up to seven-miles away. Some studies show humans also detect pheromones, but the effect seems to require close encounters.
Snakes
A snake flicking its forked tongue might look ominous to us, but it's just the animal sniffing its surroundings. A snakes use its tongues to collect particles wafting in the air. The coated tongue is then dipped into special pits in the roofs of the snake's mouth, called Jacobson's organs. There, the odors get processed and translated into electrical signals that are sent to the brain.
Cats
Cats have a mirror-like membrane in the backs of their eyes that lets them hunt and move in almost complete darkness. Called a "tapetum lucidum," the membrane reflects light after it has already traveled through the retina, giving the eyes another chance to nab the photons as they make their second trip.
Hummingbirds
The eyes of insects and birds are attuned to wavelengths of light outside the visible range that humans see in. Birds that appear drab to us are often radiant in colors we donet even have names for when seen in near-ultraviolet light. Telescopes like Hubble make ultraviolet images, which are colorized by technicians so we can enjoy them.
Boa
Temperature-sensitive organs located between the eyes and nostrils of boas and pit vipers allow the snakes to sense the body heat of their prey. There is one located on each side of the snakes' head, so the animals can perceive depth and strike with deadly accuracy even in complete darkness.
Sharks
Never play hide-and-seek with a shark because you'll lose. Sharks have special cells in their brains that are sensitive to the electrical fields other creatures generate. This ability is so refined in some sharks that they can find fish hiding under sand by the weak electric signals their twitching muscles emit.
Bats
Bats avoid obstacles and nab insects on the wing by emitting ultrasonic squeaks and interpreting the echo the sound waves make after bouncing off objects in the environment. This biological sonar, called "echolocation," is also used by dolphins to navigate murky waters.
