:: 9:08 AM by - shenghui
Let's look into some of the special "magnetic" animals right now!
A. Sea Turtle
Baby loggerhead sea turtles are able to find their way along an 8,000-mile migration route the first time they ever see it!
Scientists took some turtles off course, but they were able to find their way back with little difficulty.
Believing that some magnetic orienteering was going on, the next experiment subjected the turtles to a variety of magnetic fields that differed from the earth's natural field.
These turtles went off course.
Exposure to a magnet that mimicked the earth's field set them right again - proof that the turtles can detect the Earth's magnetic field and use it to navigate.
B. Honey Bees
This small creature actually has tiny compasses in its tummy, that sense the Earth's magnetic field.
Honeybees have tiny paramagnetic particles in their bodies; they are inside cells inside the bees' tummy.
Depending on whether they are lined up side-by-side, or end-to-end, these paramagnetic particles can, as the external magnetic field changes, swell or shrink.
These paramagnetic particles are attached to the "walls" of the cells that they are in, so as the paramagnetic particles change change, so do the cell walls.
And nerves, attached to the outside of these cells, carry signals up to the honeybee's brain.
So the magnetic cells in the bees tummy are like tiny onboard compasses.
By using the paramagnetic particles of iron oxide, these honeybees can avoid getting lost on the way home, and iron out their problems with a little magnetic navigation.
Interesting isn't it?
C. Homing Pigeons
Fondly known as our carrier pigeon - she is "magnetic" too?!
Yes, research has been performed with the intention of discovering how pigeons, after being transported, can find their way back from distant places they have never visited before.
Many researchers believe that homing ability is based on a "map and compass" model, with the compass feature allowing birds to orient and the map feature allowing birds to determine their location relative to a goal site.
It is true that birds can detect a magnetic field, to help them find their way home.
On top of magnetic navigation, some research also indicates that homing pigeons navigate by following roads and other man-made features, making 90 degree turns and following habitual routes, much the same way that humans navigate.
Amusing, aren't they?
Here comes to the end of this learning website.
But do look into the next post and test your knowledge you have acquired so far about Physics and Animals with my puzzle!
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.
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, tuna, salmon etc all have magnetic sense.
Researchers have found that each of these animals has deposits of magnetite in their nervous systems.
Magnetite, small magnet-like crystals, align themselves with magnetic fields and might act like microscopic compass needles.
A large variety of animals possess a magnetic sense.
Migratory birds use magnetic clues to find their way south in fall and north in spring.
Salamanders and frogs use the magnetic field orientation when they have to find the direction of the nearest shore quickly e.g. when they sense danger.
do you know?
Some species of bacteria even reply on the magnetic field to orient themselves.
We shall know more case studies about animals using magnetism to navigate in the next post!
:: 8:26 AM by - shenghui Electric Animals and Human
Are they dangerous?
Can they kill us?
Let's explore! (:
Eels and People:
Deaths to people from electric eel shocks are very rare, but not unheard of.
Repeated shocks have been known to cause respiratory and heart failure.
People drowning after being stunned is more common.
Do you know?
However, releasing repeated charges will wear out an eel, making them vulnerable to capture.
INTERESTING FACTO!
Adult eels will generally tolerate one another, but young eels will fight for supremacy and eels of any age will attack other fish.
Stingrays with People:
There are no confirmed human fatalities from interactions with electric rays, but a shock from one is more than enough to knock down a full grown human.
There are even reports of ancient Greeks and Romans taking live rays from the sea and using weaker electrical charges to numb the pains of childbirth and various simple surgeries.
Romans were also known to use the torpedo fish’s electrical currents in the treatment of headaches and more commonly, gout.
Electric Catfish and People:
It is not at all uncommon to find electric catfish for sale to the public, although no successful captive breeding program has been founded.
Even a tiny two-inch catfish can deliver a potent charge, making their handling very tricky.
The electric catfish has co-existed with man for countless centuries.
There are pictures of electric catfish on Egyptian tombs dating back over 5000 years.
The ancient Egyptians harbored a healthy respect for the electric catfish because of its shocking capabilities.
Its name translates to mean “he who has saved many in the seas.”
Presumably, this was due to the loss of many nets of fish when they were dropped back into the water following a discharge from a netted catfish.
Interesting yea?
There are many more animals which will stun us with magnetism!
Electric fields are used in numerous ways by animals. 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.
In this following post, we will be investigating these following interesting "attractive" yet dangerous animals (;
A. Electric Eel
Do you know?
An electric eel will not venture to the sea because the salt effectively causes a short circuit during electrical attacks.
It has an excellent sense of hearing and also a Sachs organ, which has been linked to electrolocation.
This organ is able to emit a low voltage charge of about 10 V!
The electric eel has poor vision and depends on its weak electric charge to navigate.
Its electric organ is made up of plates of musclefibres connected in a series down its long body.
Each electric plate generates less than a volt of electricity, but when combined together, they generate a stronger charge used to stun and kill prey.
The eel not only uses these weak charges for orientation, as well as locating prey and potential mates.
Some scientists feel it is also used in a rudimentary form of communication.
When the eel becomes upset or is preparing to attack a prey animal, its brain signals the electric cells in these electric organs.
An ion channel is opened and positively charged sodium flows into the organs, reversing the charge for a moment.
The product of this sudden shift of disturbance in voltage creates an electric current.
How big is the charge given off by an electric eel?
Let's see what an electric eel can do to a Christmas Tree!
B. Electric Stingray
Electric stingrays use electricity for attack and/or defense.
This electric animal hangs suspended in water, waiting for a prey fish to come within range.
When an unsuspecting fish comes into range, the ray lunges forward in a quick motion and wraps the prey in the folds of its pectoral fins.
It will kick with its tail and roll repeatedly in order to tighten its grip, all the while delivering electric shocks to its victim.
Another common tactic involves burying itself in the sand during the daylight hours and rearing out to snatch passing fish.
Maximum voltage during initial attack is 45 volts.
do you know?
Temperature of water will alter the speed of the pulses issued by the ray.
The warmer the water, the faster the attack.
C. Electric Catfish
Catfish use electricity in a variety of ways.
Like the electric eels, catfish are able to send weak electric charges into the water to serve as a type of radar, helping the fish to navigate in its murky environment.
do you know?
The fish emits a continuous electric current as it swims or rests.
Special receptors beneath its skin allow it to detect any disruptions in the current, making it an effective navigational tool.
It can also be used for finding prey. It uses its more powerful current to stun prey and to defend itself when it is attacked by predators.
The electric catfish can generate a powerful charge up to 350 volts.
do you know?
Charges can last up to thirty seconds! These can prove deadly to its prey, but have no effect on the catfish itself!
Electric catfish are vicious defenders of their territory and will attack other catfish upon sight.
Often the battle begins with open mouth displays and thrashing.
Ironically, the fish seldom discharge when fighting their own species.
So don't you dare to upset any animals again - they might just possess electricity enough to kill you! :D
They use naturally generated infrasound, from sources such as turbulent airflow over mountain ranges, as a navigational aid.
B. Elephants
Infrasound may also be used for long-distance communication in African elephants.
They can produce infrasound waves that travel through solid ground and are sensed by other herds using their feet, although they may be separated by hundreds of kilometres.
These calls range from 15-35Hz and can be as loud as 117dB, allowing communication for many kilometres, with a possible maximum range of around 10km.
These calls may be used to coordinate the movement of herds and allow male elephants to find mates.
They use infrasound - which can travel vast distances through the ground, air, and water - to carry on long-distance conversations.
Researchers have homed in on these "invisible" communications in just the last few decades, as sophisticated microphones and recording equipment allowed them to listen in.
Now, infrasound researchers wonder whether some animals can hear danger approaching. For instance, big storms such as hurricanes produce their own distinctive infrasonic signature.
Similarly, earthquakes can produce several distinct infrasound pulses that can travel thousands of miles and much faster than water.
Thus, tsunamis, also triggered by earthquakes, hit the shores only after infrasound.
C. Alligators
Alligator researchers are cracking the code that these huge reptiles use to signal their mates.
They have learned that alligators can produce an array of infrasonic signals by vibrating air inside special sound-producing sacs in their chins.
+ 
?! 
