Newsademic British English edition 260

n im a l
 
com passes
Some birds are known to migrate 
for very long distances. Several 
whale, fish and turtle species swim 
thousands o f kilometres to the places 
where they give birth to their young 
or lay their eggs. How these animals 
knowwhichway to travel is a mystery.
M agnified fru it fly
Many scientists suspect that 
migrating animals use the Earth’s 
magnetic field to work out their 
direction o f travel. Others may use 
the position o f the Sun. The Earth 
is similar to a huge magnet. It’s the 
planet’s magnetic field that makes 
a compass needle point towards the 
north. Magnetic north and south are 
near to the North and South Poles.
Researchers in China now believe 
that they have discovered a biologi­
cal ‘compass’ in fruit flies. They call 
it a biocompass. Fruit flies seem to 
know in which direction they need 
to travel. The Chinese researchers’ 
work suggests that many animals 
have their own internal biocompass. 
This compass, they say, is how the 
animals know where they are and 
where they are going.
Other scientific work in the past 
seemed to show that some animals 
could sense magnetic fields in certain 
circumstances. It happened when 
electrons fell on a protein found in 
the eye. These proteins can detect

---

26th November 2015 
N e w s a d e m ic .co m ™
 - British English edition 
page 
17
light. Therefore they could be a con­
nection between sunlight and the 
magnetic field. Some molecules in 
the body contain iron. Another idea 
was that this iron acts like a magnet 
when exposed to a magnetic field.
The Chinese researchers did not 
think these explanations solved the 
mystery. However, they thought the 
answer might be a combination of 
both. The researchers studied genes 
from fruit flies. They found sev­
eral proteins that contain iron. The 
researchers then performed sev­
eral tests on these proteins. These 
showed that the iron-based protein 
would bind, or attach, to the light­
detecting proteins.
Proteins are a type o f molecule. In 
living organisms they perform dif­
ferent roles, or do certain jobs. For 
example, proteins carry out instruc­
tions that are ‘given out’ by genes. 
The protein with the iron formed 
a rod-like shape amongst the light 
detecting proteins. The research­
ers called this iron-based protein a 
magnetoreceptor, or MagR. Further 
tests showed that M agR lines up 
with the E arth’s magnetic field. The 
researchers believe that this protein 
is the fruit fly’s biocompass.
M igrating geese (USFWS)
The Earth’s magnetic field is 
not the same strength all around 
the globe. It is weaker over South 
America, yet stronger over Canada, 
Siberia, in northern Russia, and parts 
o f Antarctica’s coastline. W hat’s 
more, the field’s direction and angle
changes. It goes straight down at the 
North Pole, is horizontal, or flat, at 
the Equator, and points straight up 
at the South Pole. The researchers 
think that a biocompass can detect 
all these differences.
The researchers say that they 
have found M agR in pigeons’ eyes. 
It is also in butterflies, rats, whales, 
and, in very small amounts, humans. 
They now suspect that all animals 
have some type o f biocompass. More 
work is needed to find out if this is 
true. The researchers say that they 
also want to discover how biocom­
passes send ‘signals’ to the brain. □
R