Animals have developed amazing
adaptations to their environments. Many different types of energy & senses exist
in the environment, some of which humans cannot detect. Here are some examples
of how some animals sense the outside world.
•Can detect small movement through 5 cm of earth.
•Can see polarized light.
•Can detect warmth of an animal from about 16 cm away using its "nose-leaf".
•Bats can also find food up to 18 ft. away and get information about the type of
insect using their sense of echolocation.
•Can see light between wavelengths 300 nm & 650 nm.
•Have taste receptors on their jaws, forelimbs and antennae.
•Worker honey bees have a ring of iron oxide in their abdomens that may be used
to detect magnetic fields. They may use this ability to detect changes in the
earth's magnetic field and use it for navigation.
•Can see polarized light.
•Has taste receptors on its feet.
•The butterfly has hairs on its wings to detect changes in air pressure.
•Using vision, the butterfly Colias can distinguish two points separated by as
little as 30 microns.
•Has hearing range between 100 and 60,000 Hz.
•Olfactory membrane about 14 sq. cm. For comparison, humans have an olfactory
membrane of about 4 sq. cm.
•The eyes of the chameleon can move independently & can see in two different
directions at the same time.
•Can detect movement as small as 2,000 times the diameter of a hydrogen atom.
•Has hairs on claws and other parts of the body to detect water current and
•Many crabs have their eyes on the end of stalks.
•Can hear using their legs; sound waves vibrate a thin membrane on the cricket's
•Has olfactory membrane up to 150 sq. cm.
•Can hear sound as high as 40,000 Hz.
•Like bats, dolphins use echolocation for movement and locating objects.
•Can hear frequencies up to at least 100,000 Hz.
•Eye contains 30,000 lenses.
•Entire body covered with chemoreceptors ( taste receptors ).
•Has hearing range between 1 and 20,000 Hz. The very low frequency sounds are in
the "infrasound" range. Humans cannot hear sounds in the infrasound range.
•Can see a 10 cm. object from a distance of 1.5 km.
•Have a "lateral line" system consisting of sense organs ("neuromasts") in
canals along the head and trunk. These receptors are used to detect changes in
water pressure and may be used to locate prey and aid movement.
•Some fish can see into the infrared wavelength of the electromagnetic spectrum.
Fish ( Deep sea )
•Only have rods in the retina: 25 million rods/sq. mm. Perhaps they need this
high density of photoreceptors to detect the dim biolumninescence that exists in
the ocean depths.
Fish ("Four-eyed Fish" Anableps microlepis)
•Can see in air and water simultaneously. Each eye is divided by flaps, so there
is one opening in the air and one in the water.
•Eye has a flicker fusion rate of 300/sec. Humans have a flicker fusion rate of
only 60/sec in bright light and 24/sec in dim light. The flicker fusion rate is
the frequency with which the "flicker" of an image cannot be distinguished as an
individual event. Like the frame of a movie...if you slowed it down, you would
see individual frames. Speed it up and you see a constantly moving image.
•Blowflies taste with 3,000 sensory hairs on their feet.
•Has an eardrum (tympanic membrane) on the outside of the body behind the eye.
•Normal vision for people is 20/20. A hawk's vision is equivalent to 20/5. This
means that the hawk can see from 20 feet what most people can see from 5 feet.
(Scientific American, April 2001, page 24)
•Can hear frequencies between 1,000 and 100,000 Hz. By comparison, we humans can
hear frequencies between 20 and 20,000 Hz.
•Attracted to host by human body odor ( especially the foot odor), carbon
dioxide, body heat and body humidity.
•Retina contains 20 million photoreceptors.
•The eye has a flicker fusion frequency of 70/sec in bright light.
•The pupil of the eye is rectangular.
•Has a flat cornea that allows for clear vision underwater. Penguins can also
see into the ultraviolet range of the electromagnetic spectrum.
•Tongue contains 15,000 taste buds. For comparison, the human tongue has 9,000
•With eyes mounted laterally on their heads, pigeons can view 340
degrees...everywhere except in back of their heads.
•Can detect sounds as low as 0.1 Hz.
•Tongue contains 17,000 taste buds.
•Has hearing range between 1,000 and 90,000 Hz.
•Each eye can move independently.
•Can detect air moving at only 0.072 km/hr with special hairs on its pincers.
•Can have as many as 12 eyes.
•Has specialized electrosensing receptors with thresholds as low as 0.005 uV/cm.
These receptors may be used to locate prey. The dogfish can detect a flounder
that is buried under the sand and emitting 4 uAmp of current.
•Some sharks can detect fish extracts as concentrations lower than one part in
•Some sharks sense light directly through the skull by the pineal body.
•The tongue of snakes has no taste buds. Instead, the tongue is used to bring
smells and tastes into the mouth. Smells and tastes are then detected in two
pits, called "Jacobson's organs", on the roof of their mouths. Receptors in the
pits then transmit smell and taste information to the brain.
•Snakes have no external ears. Therefore, they do not hear the music of a "snake
charmer". Instead, they are probably responding to the movements of the snake
charmer and the flute. However, sound waves may travel through bones in their
heads to the middle ear.
•Snakes have no moveable eyelids. Instead, they have a clear, scale-like
membrane covering the eye.
•Many spiders have eight eyes.