Randall Twede
Did You Hear That?
Everyone knows about the five senses: sight, hearing, smell, taste, and touch. Through these five senses, we experience the world around us. We see the stars twinkling at night; hear the wail of a police siren; smell the aroma of a freshly baked pie; taste the bitterness of an aspirin; and feel the grip of a firm handshake. It was once believed that these were the only physical senses that existed. We now know, however, that this is only true of human beings.
For the most part, other animals have the same senses that we do. Sometimes these senses are very well developed; even what you would call amazing. Let's take a closer look at each of these five senses.
Birds reign supreme when it comes to vision. An eagle can spot a mouse from hundreds of meters in the air. A buzzard can see small rodents from a height of 15,000 ft. A falcon can see a 10 cm. object from a distance of 1.5 km. Owls have nocturnal vision that allows them to see better at night. Penguins, and some other birds, can see ultraviolet radiation. At the other end of the spectrum, some fish can see into the infrared.
Humans can hear frequencies between 20 and 20,000 Hz. Elephants have a hearing range between 1 and 20,000 Hz. A pigeon can detect sounds as low as 0.1 Hz. Mice can hear frequencies between 1,000 and 100,000 Hz. The Noctuid Moth has a hearing range between 1,000 and 240,000 Hz. Bats and porpoises send out ultra-high frequency sounds and listen for the echoes. This ability, referred to as echolocation, helps them avoid obstacles.
Dogs have a highly developed sense of smell. It is claimed that a Bloodhound's sense of smell is three million times more sensitive than ours is. They have been known to follow a scent up to five days old. The male Silkworm Moth can detect the female's pheromones at distances of up to 11 km.
Wine tasters and food critics pride themselves on having a discriminating palate. However, their sense of taste is primitive compared to a catfish, which has ten times as many taste buds as a human. Rabbits and pigs also have more taste buds than we do.
Some areas of the human body are very sensitive to touch; yet there are animals that surpass us in this sense as well. The Star-nosed mole's nose, which is quite small, has six times as many touch receptors as a human hand.
Some animals, however, have unique sensory organs unlike any possessed by man.
For example, pit vipers and some other snakes have pit organs that can sense infrared radiation from a considerable distance. They use this sense to hunt their warm-blooded prey.
The Lateral Line System, found in most fish and some aquatic amphibians, is sensitive to changes in water pressure. A swimming fish creates pressure waves that can be detected by the lateral lines of other fish. They can also detect an obstacle because it distorts the pressure waves around the fish's body. Similarly, a butterfly has hairs on its wings to detect changes in air pressure.
Sharks not only have a Lateral Line System, but they also have bio-electrical sensors known as the ampullae of Lorenzini. These sensors, located near the mouth and nose on the shark's snout, enable a shark to detect the extremely faint electrical currents generated by the Earth's magnetic field and by other living creatures. They are so sensitive, a shark can detect the heart beat of a perfectly still mammal from a distance of nine feet, just by sensing electrical currents the heartbeat sends out into the water! The ampullae also seem to function like an internal compass, helping sharks to orient themselves in relation to the earth's electro-magnetic fields.
How homing pigeons find their way home is still a mystery. They have been known to reach home by flying over 1000 miles in two days time through unfamiliar territory. The most popular theory is that they can, like the shark, detect the earth's electro-magnetic fields.
It's all about survival: survival of the individual, and survival of the species. In order to survive as an individual, a creature must eat and avoid being eaten. It is also important that one can avoid dangers like falling off a cliff (or flying into one). To survive as a species, reproduction is essential. If an eagle's eyesight were as poor as a human's is, it would starve to death. If bats lacked their echolocation ability, many would injure themselves during their nightly excursions. If the male Silkworm Moth's ability to sense pheromones was as limited as mine is, the species would die out.
