Senses in the dark

Animal strategies in the dark

Here’s an interesting collection of facts about the amazing senses that animals can use no matter whether it’s light or dark.

Bats

Echolocation in bats

Echolocation in bats

Bats can find food (insects) up to 18 ft. away and get information about the type of insect, using echolocation.  They can hear frequencies between 3,000 and 120,000 Hz.  In comparison, humans can hear frequencies between 20 and 20,000Hz.  Bats can also detect the warmth of an animal from a distance of 16cm.

 

Cat and dog. Photo: Bev Lloyd-Roberts

Cat and dog. Photo: Bev Lloyd-Roberts

Cats

Cats have a hearing range between 100 and 60,000 Hz.  Their olfactory membrane is about 14 square centimeters.  In comparison, humans’olfactory membrane is only 4 square centimeters.

Dogs

Has an olfactory membrane of up to 150 square centimeters.  It can can hear sound as high as 40,000 Hz.

Cockroaches

Cockroaches can detect movement as small as 2,000 times the diameter of a hydrogen atom.

Crickets

Crickets hear using their legs, as sound waves create a vibration on a thin membrane of their front legs.

Earthworm – the crawling tongue

The entire body of an earthworm is covered with chemoreceptors, similar to taste receptors.

Elephant

The hearing range of an elephant is between 1 and 20,000 Hz.  The very low frequency sounds are in the infrasound range, which humans cannot hear.

Fish

Lateral line in sharks

Lateral line in sharks

Fish 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.

 

Star-nosed mole

Star-nosed mole

Star nosed mole

The star-nosed mole uses its fleshy star nose for hunting.  It has 100,000 nerve fibers that run from the star to the brain.  This is almost six times more than the touch receptors in the human hand.

 

 

Shark

Has specialized electromagnetic receptors with thresholds as low as 0.005 microvolts/cm.  These receptors may be used to locate pray.  The dogfish can detect a flounder that is buried under the sand and emitting 4 microamperes of current.

Snakes

Pit-vipers have a heat-sensitive organ between the eyes and the nostrils, about 0.5cm deep.  This organ has a membrane, containing 7000 nerve 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 the mouse is 10 degrees centigrade above the outside temperature.

Snakes do not have 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 trvel through bones in their heads to their middle year.