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Animal Senses
By peace | May 10, 2007
Insect-eating bats have very sensitive hearing that allows them to hunt and navigate in darkness using echolocation. They make high-pitched sounds then swivel their ears to pinpoint the source of echoes, which lead them to their prey.
Animals use their sense to find out about the world around them. Most have the same five senses as humans but some have extra senses, such as echolocation. Some animals have developed amazing adaptations to their environments. Many different types of energy exist in the environment, some of which humans cannot detect.
Here are some examples of how some animals sense the outside world and the anatomical structures that allow them to do so.
1. Ecolocation
Bats, whales and dolphins, which hunt in darkness or murky water, make sounds then listen for echoes to track their prey. They use ecolocation to navigate their surroundings. The same technique helps them to navigate and avoid collisions with objects. Each of these animals emits high-frequency sound pulses and, in turn, detects the echoes produced by those sounds. Special ear and brain adaptations enable them to build a three-dimensional picture of their surroundings, much like radar. Bats, for example, have enlarged ear flaps that gather and direct sound towards thin, supersensitive eardrums.
How does echolocation help with hunting?
Hunting bats and dolphins make streams of clicking sounds, which spread out through the air or water. The sound vibrations bounce back off objects such as flying insects or shoaling fish. The hunter uses its keen hearing to listen out for the returning echoes. These allow it to pinpoint the whereabouts of its victims, so that it can home in on its prey.
2. Infrared Vision
Some animals can see quite clearly at night even when there is no moon. The large eyes of nocturnal hunters, such as owls, are designed to make the most of very dim light. Many animals active at night also have extremely good senses of hearing and smell.
The most interesting feature of nocturnal animals is the size of their eyes. Large eyes, with a wider pupil, larger lens and increased retinal surface collect more light. Some animal species have evolved tubular eyes as a means of increasing their size. Many nocturnal animals cannot move their eyes within the orbit. Instead, they have evolved extraordinary rotational ability in the neck. Owls, for example, can rotate their neck through 270° & this aids their vision.
Some animals of the night have acquired a spherical lens and widened cornea to compensate for reduced eye movement. This combined with a wide cornea increases the animals field of view allowing the head and eyes to remain motionless.
Rattlesnakes and other pit vipers use their eyes to see during the day. But at night they use infrared sensory organs to detect and hunt warm-blooded prey. These infrared “eyes” are cuplike structures that form crude images as infrared radiation hits a heat sensitive retina.
3. Electric Sense
Electric fields are used in numerous ways by animals. Some aquatic animals, including sharks, can pick up tiny electrical signals given off by their prey. Electric eels and some rays have modified muscle cells that produce an electric charge strong enough to shock and sometimes kill their prey. Other fish use weaker electric fields to navigate murky waters or to monitor their surroundings. For instance, bony fish and some frogs have a lateral line, a row of sensory pores in the skin, that enables them to detect electrical current in water.
4. Magnetic Sense
Together, the flow of molten material in the earth’s core and the flow of ions in the atmosphere generate a magnetic field that surrounds the earth. Amazingly, a number of animals are able to sense this magnetic field. It is believed that many migratory animals can detect the Earth’s magnetic field to help find their way. Just as a compass helps us navigate by detecting magnetic north, animals who possess magnetic sense are able to identify direction and navigate long distances. Behavioral studies have revealed that many animals including honey bees, sharks, sea turtles, rays, homing pigeons, migratory birds, tuna, and salmon all have magnetic sense.
Can Animals Sense Natural Disasters?
Animals have keen senses that help them avoid predators or locate prey. It is thought that these senses might also help them detect pending disasters. Several countries have conducted research on the detection of earthquakes by animals. There are two theories as to how animals may be able to detect earthquakes. One theory is that animals sense the earth’s vibrations. Another is that they can detect changes in the air or gases released by the earth. There has been no conclusive evidence as to how animals may be able to sense earthquakes. Some researchers believe the animals at Yala National Park were able to detect the earthquake and move to higher ground before the tsunami hit, causing massive waves and flooding.
Other researchers are skeptical about using animals as earthquake and natural disaster detectors. They site the difficulty of developing a controlled study that can connect a specific animal behavior with an earthquake occurrence. The United States Geological Survey (USGS) officially states: *Changes in animal behavior cannot be used to predict earthquakes. Even though there have been documented cases of unusual animal behavior prior to earthquakes, a reproducible connection between a specific behavior and the occurrence of an earthquake has not been made. Because of their finely tuned senses, animals can often feel the earthquake at its earliest stages before the humans around it can. This feeds the myth that the animal knew the earthquake was coming. But animals also change their behavior for many reasons, and given that an earthquake can shake millions of people, it is likely that a few of their pets will, by chance, be acting strangely before an earthquake.
Although scientists disagree as to whether animal behavior can be used to predict earthquakes and natural disasters, they all agree that it is possible for animals to sense changes in the environment before humans. Researchers around the world are continuing to study animal behavior and earthquakes. It is hoped that these studies will help to aid earthquake predictions.
Do animals have better senses than us?
Many animals have far keener senses than humans. Sight is our most important sense, but birds such as falcons have much sharper vision. Some insects can detect ultraviolet light, which we cannot see. A bloodhound’s nose is many times more sensitive than a human’s. Bats, whales and elephants can detect very high or low sounds that we cannot hear.
