Some animals have developed amazing adaptations to theirenvironments. Here are some examples of how some animals sense the outside world and the anatomical structures that allow them to do so.
Ants
- Can detect small movement through 5 cm of earth.
Bats
- Can detect warmth of an animal from about 16 cm away using its "nose-leaf".
- Bats can also find food (insects) up to 18 ft. away andget information about the type of insect using their sense ofecholocation.
Bees
- Can see light between wavelengths 300 nm and 650 nm.
- See the world through the eyes of a honeybee.
- Have chemoreceptors (taste receptors) on their jaws, forelimbs and antennae.
- Worker honey bees have 5,500 lenses ("ommatidia") in each eye.
- Worker honey bees have a ring of iron oxide ("magnetite") in theirabdomens that may be used to detect magnetic fields. They may use thisability to detect changes in the earth's magnetic field and use it fornavigation.
Butterfly
- Has chemoreceptors (taste receptors) onits feet.
- The butterfly has hairs on its wings todetect changes in air pressure.
Buzzard
- Retina has 1 million photoreceptors per sq. mm.
- Can see small rodents from a height of 15,000 ft.
Cat
- Has hearing range between 100 and 60,000 Hz.
- Olfactory membrane about 14 sq. cm. For comparison, humans havean olfactory membrane of about 4 sq. cm.
Chameleon
- The eyes of the chameleon can move independently. Therefore, itcan seein two different directions at the same time.
Cockroach
- Can detect movement as small as 2,000 times the diameter of ahydrogen atom.
Crab
- Has hairs on claws and other parts of the body to detect watercurrent and vibration.
Crayfish
- Has sensory hairs that can detect movement of 0.1 microns (at 100Hz frequency).
Dog
- Has olfactory membrane up to 150 sq. cm. Find out how a dog'ssense of smell is used in police work.
- Can hear sound as high as 40,000 Hz.
Dolphin
- Like bats, dolphins use echolocation for movement and locatingobjects.
- Can hear frequencies up to at least 100,000 Hz.
Dragonfly
- Eye contains 30,000 lenses.
Earthworm
- Entire body covered with chemoreceptors(taste receptors).
Elephant
- Has hearing range between 1 and 20,000 Hz. The very low frequencysounds are in the "infrasound" range. Humans cannot hear sounds in the infrasound range.
Falcon
- Can see a 10 cm. object from a distance of 1.5 km.
Fish
- Some can detect the L-serine (a chemical found in the skin ofmammals) diluted to 1 part per billion.
- Have a "lateral line" system consisting of sense organs ("neuromasts")in canals along the head and trunk. These receptors are used to detectchanges in water pressure and may be used to locate prey and aidmovement.
- Some fish can see into the infrared wavelength of the electromagneticspectrum.
Fish (Catfish)
- Has 3 or 4 pairs of whiskers, called barbels, to find food. The catfish also has approximately 100,000 taste buds. (Humans have only 10,000 taste buds.)
Fish (Deep sea)
- Only have rods in the retina: 25 million rods/sq. mm. Perhapsthey need this high density of photoreceptors to detect the dimbiolumninescence that exists in the ocean depths.
Fish (Drum Fish)
- Collects underwater sound vibrations with an air bladder. Thesignals are then sent from the air bladder to the "weberian apparatus" inthe middle ear and then to the inner ear. Hair cells in the inner earrespond to the vibration and transmit sound information to the fishbrain.
Fish ("Four-eyed Fish" Anablepsmicrolepis)
- Can see in air and watersimultaneously. Each eye is divided by flaps, so there is one opening inthe air and one in the water.
Fly
- Each eye has10,000 lenses.
- Eye has a flicker fusion rate of 300/sec. Humans have aflicker fusion rate of only 60/sec in bright light and 24/sec in dimlight. The flicker fusion rate is the frequency with which the "flicker" of an image cannot be distinguished as an individual event. Like theframe of a movie...if you slowed it down, you would see individual frames.Speed it up and you see a constantly moving image.
- Blowflies tastewith 3,000 sensory hairs on their feet.
Frog
- Hasan eardrum (tympanic membrane) on the outside of the body behind theeye.
Giant Squid
- Eye is 40 cm in diameter.
- Retina can contain up to 1 billion photoreceptors.
Grasshopper
- Has hairs ("sensilla") all over the body to detect airmovement.
- Can hear up to 50,000 Hz.
Iguana
- Able to detect the temperature of sand within 2 degrees F. Thistemperature is needed for the iguana to lay its eggs.
Mice
- Can hear frequencies between 1,000 and 100,000 Hz. Bycomparison, humans can hear frequencies between 20 and 20,000 Hz.
Mole (Star-nosedMole)
- Uses its fleshy star nose for hunting. The Star-nosed mole has100,000 nerve fibers that run from star to the brain. This is almost sixtimes more than the touch receptors in the human hand.
Mosquito- Attracted to host by human body odor (especially foot odor),carbon dioxide, body heat and body humidity.
Moth
- Noctuid Moth has a hearing range between 1,000 and 240,000Hz.
- Emperor Moth can detect pheromones up to 5 km. distant.
- Silkworm Moth can detect pheromones up to 11 km. distant.This moth can detect pheromones in concentrations as low as 1molecule of pheromone per 1017 molecules of air.
Octopus
- Retina contains 20 million photoreceptors.
- The eye has a flicker fusion frequency of 70/sec in brightlight.
- The pupil of the eye is rectangular.
- Has chemoreceptors (taste receptors) on the suckers of their tentacles. By tasting this way, anoctopus does not have to leave the safety of its home.
Penguin
- Hasa flat cornea that allows for clear vision underwater. Penguins can alsosee into the ultraviolet range of the electromagnetic spectrum.
Pig
- Tongue contains 15,000 taste buds. For comparison, the humantongue has 9,000 taste buds.
Pigeon
- With eyes mounted laterally on their heads, pigeons can view 340degrees...everywhere except in back of their heads.
- Can detect sounds as low as 0.1 Hz.
Platypus
- Has electric sensors in its bill that can detect 0.05 microvolts.Other receptors in the bill are for touch and temperaturedetection.
- The cochlea of the inner ear is coiled only a quarter of aturn. In man, the cochlea is coiled about 2.7 times.
Rabbit
- Tongue contains 17,000 taste buds.
Rat
- Has hearing range between 1,000 and 90,000 Hz.
Seahorse
- Each eye can move independently.
Scallop
- Has100 eyes around the edge of the shell. These eyes are probably used todetect shadows of predators like the starfish.
Scorpion
- Can detect air moving at only 0.072 km/hr with special hairs onits pincers.
- Can have as many as 12 eyes.
Shark
- Has specialized electrosensingreceptors with threshold as low as 0.005uV/cm. These receptors may be used to locate prey. The dogfishcan detect a flounder that is buried under the sand and emitting 4 uAmp of current.
Snakes
- Pit-vipers have a heat-sensitive organ between the eyes and thenostrils about 0.5 cm deep. This organ has a membrane containing 7,000nerve endings that respond to temperature changes as small as 0.002-0.003 degrees centigrade. A rattlesnake can detect a mouse 40 cm away if themouse is 10 degrees centigrade above the outside temperature.
- The tongue of snakes has no taste buds. Instead,the tongue is used to bring smells and tastes into the mouth. Smells andtastes are then detected in two pits, called "Jacobson's organs", on theroof of their mouths. Receptors in the pits then transmit smell and tasteinformation to the brain.
- Snakes have no external ears. Therefore, they do not hear the musicof a "snake charmer". Instead, they are probably responding to themovements of the snake charmer and the flute. However, sound waves maytravel 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.
Sparrow
- Retina has 400,000 photoreceptors per sq. mm.
Starfish
- Arms covered with light sensitive cells. Light that projects onan "eyespot" on each arm causes the arm to move.
For more information, see:
InsectsAmazing Sense of Smell
Two good books for information about the amazing senses of animals are:
- Jillyn Smith, Senses & Sensibilities, John Wiley & Sons,New York, 1989, pp. 230 (Grades 9-12).
- John Downer, Supersense. Perception in the Animal World, Holtand Co., New York, 1988, pp. 160. (Grades 9-12).