p18-20_final 8/7/12 4:38 PM Page 1
C
M
Y
CM
MY
CY CMY
K
YOUNG SCIENTIST SECTION
Snake
self-defence and
human safety in
snake encounters
BY JOVAN HSIEH
LAYOUT: ERIC LUA
“Eek!” must have been the first
reaction when most of you read
the heading. Well, so was my
initial reaction until I read more
about these creatures. I was
wowed by their instinct to
survive and their amazing
self-defence mechanisms.
What are snakes?
Snakes are elongate, legless
reptiles that can be
differentiated from legless
lizards by their lack of eyelids
a n d ex terna l ears . To
accommodate their narrow
bodies covered in scales, snakes'
paired organs (such as kidneys)
appear one in front of the other,
instead of side by side, and
most have only one functional
lung.
Self-protection mechanisms
Playing Dead
When they sense danger, some snakes roll onto their backs and
‘play dead’. They will open their mouths and let their tongues
hang out. To appear injured, some snakes can make the inside of
their mouths bleed even though they are not hurt.
Further, the snake’s heart rate will significantly slow down from
50-80 BPM (beats per minute) to just 3-15 BPM! While squirming
on its back as if dying, special glands near its tail emit a liquid
that stinks. Finally, it lies completely still. Not only does the snake
look dead, it smells dead too! The Hognose Snake is one such
expert at this.
Source: Andre Chatroux
Grass Snake
18 singapore
No 123
Source: Piet Spaans Viridiflavus
Grass Snake Playing Dead
p18-20_final 8/7/12 4:38 PM Page 2
C
Camouflage
Snakes camouflage to hunt and
hide. They have markings on
their body to blend with their
environment, and that helps
them hide from predators or
hunt prey.
M
Y
CM
MY
Venom vs Poison
Often, people get venom and
poison mixed up. The
distinction is in the method of
administration. Poison needs to
be ingested or absorbed. It is
ge n e ra l l y s e c re te d a n d
distributed over a greater area.
Can you find the camouflaged snakes in the 4 images below?
CY CMY
K
Venom, however, can only be
injected via stings or fangs.
When a snake bites, its fangs
puncture the victim's skin and
inject the venom into a localised
part of the victim’s body.
The effects of snake venom
depend on the nature and the
amount of venom administered,
and can kick in within minutes
to hours.
The three distinct types of
venom and how they affect the
body:
1)
Neurotoxin: A group of
toxins which target the
nervous system and brain,
resulting in paralysis,
incoherence, seizures,
respiratory failure and
ultimately death. Mambas,
cobras and coral snakes can
deliver this venom.
2)
Cytotoxin: This causes tissue
damage and premature
death of cells in tissues at
the site of the bite. This
toxin destroys both tissue
and blood cells. Some
species of adders,
rattlesnakes and vipers can
administer this toxin.
3)
Haemotoxin: This attacks
the heart and cardiovascular system, causing
eventual organ failure. It
destroys the coagulant
properties of blood and, as
a result, causes severe
internal haemorrhaging. Pit
vipers, boomslangs and
vine snakes can deliver this
venom.
Source: andytang20
Gaboon Viper
Source: Kennedy Warne
Green Vine Snake
Source: Mark Bratton
Sidewinder Rattlesnake
Source: Blueag9
Mottled Rock Rattlesnake
singapore
No 123 19
p18-20_final 8/7/12 4:38 PM Page 3
C
Shake, rattle and roll
Rattlesnakes rattle their tails to
scare away predators as a final
warning of envenomation (a
threat to discharge venom), easily
identified by the loud shaking of
the noisemaker at the end of their
tail. This rattling sound deters
predators.
Mimicry
Some non-venomous snakes
pretend through their colouration
to be venomous snakes (milk
snakes mimic coral snakes); others
mimic actions of venomous
snakes (e.g. vibrating their tails
like rattlesnakes).
M
Y
CM
MY
CY CMY
K
that might be getting too close.
If you hear hissing from a snake,
beware, it may be about to strike.
This is one of the most common
attempts of self-protection.
Source: Mike Pingleton
Red Milk Snake
There are even snakes that are
two-headed. The actual head
has no distinguishing features
while the tail mimics the head.
The tail of these snakes often
looks more like a head than the
head. In an attack, the enemy
will go for the ‘head’ which is
actually the tail! Little harm will
be caused as the actual head
contains some of the vital organs
while the tail does not.
Hissing
A snake's hissing serves as a
warning to any animal or person
Snake Sense, not Sixth Sense
To survive, snakes have evolved
a combination of senses that work
together. Some snakes sense
infra-red (heat) given off by living
things. Some, such as the pit
vipers, have more developed heat
sensing organs.
Snakes have trouble seeing things
that are not moving. That is where
their forked tongue comes into
play. They use forked tongues to
‘smell’ so that they can determine
whether their food or an enemy
is close-by.
Snakes are actually deaf as they
lack external ears. So how do
snakes listen? They sense ground
vibrations instead!
STAYING SAFE IN SNAKE ENCOUNTERS
Stamp your feet
When you encounter a snake, do not panic! If you do not provoke
or corner it, chances are, it will not attack. Stand still or move
slowly away from the snake. You can also stamp your feet to create
ground vibrations, and it may deter the snake. Remember, snakes
fear us more than we fear them!
Snake Bite Emergency First Aid
In the event one gets bitten by a venomous snake, the following
steps are advised:
•
Make it a priority to get the victim to the hospital.
•
Keep the victim calm, immobilise the bitten limb (with a splint
for example) and try to keep it below the level of the heart.
•
Do not apply the 'cut and suck' technique (making cuts over
the bite and sucking out the venom). Do not add ice, alcohol,
aspirin or turpentine into the wound.
20 singapore
No 123
Did you know?
One of the largest
animals ever
documented to be
partially swallowed by
a python (Burmese
python) is an alligator
in Florida. If the
python can take on a
fierce alligator, I am
pretty sure it can take
on most other species,
including infants and
children, and there
have been such
incidents
documented.