Snake Tails
School Resources
Bob Withey
The following information is designed to be used by schools in conjunction with the
‘Snake Tails” presentation and can be freely copied for student use along with any
photographs that appear in “The Gallery”.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Reptiles – Overview for all Students and Teachers
Fact Sheet No. 1 – Years 5 to 8
Fact Sheet No. 2 – Years 5 - 8
Fact Sheet No. 3 – Senior Biology
Fact Sheet No. 4 – Senior Biology
10 Things You May Like to Know About Snakes – All Students
Questionnaire – Years 5 to 12
Please Colour Us In – Kindergarten and Year 1
Learning to Live with Reptiles – Word Puzzles – Years 1, 2, 3 & 4
As always, we value any feedback that teachers/students may have on these pages
and their content. Your comments can be forwarded to us through the “Contact
Us” tab on our Home Page.
School Resources from Australian Reptile Displays, T/A Snake Tails, April 2013
Author: Bob Withey
REPTILES
At the present time there are over 9,700 recognised species of reptiles found around the world. They
have adapted to most of the worldwide habitats from deserts to Rainforests, from swamps to mountains,
and are even found in the surface layer of the oceans.
There are five different animals that come under the banner of reptiles. These are:
1.
2.
3.
4.
5.
Lizards: over 5,900 species
Snakes: around 3,500 species
Chelions: turtles and tortoises with around 330 species
Crocodilians: 23 species
Tuataras: 2 species
Each group of animals, such as mammals, birds, fish, insects, etc. have a different combination of major
characteristics. By looking at these characteristics we can determine what group an individual animal
may belong to. Here are the 4 characteristics for all reptiles:
1. Vertebrates: all reptiles including snakes have a backbone and internal bones.
2. Lungs: all reptiles have lungs and breathe air just as we do. If a reptile goes under water, such as
a crocodile or sea snake they are simply holding their breath, just as we would.
3. Scales: all reptiles’ outer bodies are covered with scales. They do not have fur, feathers or skin.
4. Cold Blooded: all reptiles are cold blooded, or ectothermic. This does not mean that they have
cold blood or are a killer or meat eater. Simply put, it means they are animals that cannot, under
any circumstance, produce their own body heat as a warm blooded animal can. The only way a
reptile can warm itself is by using the environment such as the sun or a hot object. As the reptile
warms, they become more energetic. In other words, they are very similar to a living solar
battery.
Simply put, a reptile is an animal that is a vertebrate, has lungs, scales and is cold blooded.
There
FACT SHEET No. 1
If we wish to study Reptiles – especially snakes – we first need to determine fact from
fiction. Stories may often seem so exaggerated and absurd we can only wonder at the imagination
of the person involved while others are told with such sincerity, that we find ourselves believing
them.
When scientists and other workers require information, they usually turn to more reliable sources, such as
hospital records or the Commonwealth Serum Laboratories data or studies from Zoos, Reptile Parks, etc. The
following information and statistics have been derived from the study of these records.
In Australia, a nationwide average of around 3000 suspected envenomation victims are admitted into hospitals
each year. Usually only about 300 (10%) require treatment and antivenom. Studies of these case histories
indicate that about 80% are the result of the victim trying to kill – or sometimes catch – the offending reptile.
Snakes seldom enjoy being injured or handled and will usually retaliate quite vigorously!
The remaining 20% usually occur due to lack of awareness and carelessness – treading on snakes, climbing into
sleeping bags and finding a snake in residence, etc. – these bites are regarded as ‘accidental’, where the snake
bites only because it was surprised, injured or frightened. The bitten person usually experiences these same
feelings!
Further studies also show that certain ‘age groups’ have a higher incidence of snake bite than others – children
from about seven through to fifteen years of age, especially boys – and are known to be a ‘high risk’ group.
Studies of many thousands of case histories (from hospitals) show that snakes do not ‘chase’ people – nor do
they bite without sufficient reason, such as being injured, handled or otherwise interfered with.
If a snake is seen near human habitation, neighbours should be informed – especially if they have young
children – as well as any other people in the vicinity, and should be warned to keep away. A wildlife rescue
organisation, zoo or reptile park should be contacted. These institutions will usually send out experienced
personnel who will remove and relocate the snake.
There is a penalty (National Parks and Wildlife Act) of up to $100,000 for the unnecessary cruelty or killing of
any reptile – including venomous snakes. Usually the reptiles have wandered by accident from nearby
bushland and will seldom stray near human habitation unless attracted by numbers of rodents on which they
feed. Many species of snakes are known to stay in a given area until the food supply runs out and then, they
will move on to a new area. Most venomous species of snakes feed primarily on rats, mice, small lizards and
frogs.
In the Sydney, Gosford and Newcastle areas there are three species of snakes capable of inflicting a lethal bite.
These are the Common Brown Snake, Tiger Snake and Death Adder.
FACT SHEET No. 2
Australia has the top five deadliest snakes in the world. In descending order of potency they are:
·
·
·
·
·
Fierce Snake (also called the Inland Taipan)
Common or Eastern Brown Snake
Taipan
Tiger Snake
Death Adder
The Fierce Snake possesses venom that is regarded as being one of the most potent known. It is
49.5 times more potent than that of the Asian Cobra. One bite from a Fierce Snake could result in
over 1,000 lethal human doses.
If bitten, the correct method of first aid is to apply a tight, constrictive bandage from the bite area,
towards the heart. Most bites occur on the hands and feet. Squeezing an area of skin (without
letting go) may also restrict the movement of venom. This should be done if bitten on the face or
trunk of the body at the bite site, where a pressure bandage cannot be applied. These methods of
First Aid should be used with any venomous bite eg Funnel Web Spider, Blue Ringed Octopus, etc.
Applying pressure stops the lymphatic system from working so it cannot transport the venom into
the blood stream where it will affect the vital organs of the body.
Antivenin is produced by slowly ‘immunising’ horses with increasing doses of diluted venom to a
high level. The resulting antibodies are separated from the blood, treated and purified and the
result is Antivenin.
Antivenin should only be administered in a hospital environment as it has caused fatalities from
anaphylaxis (shock) when given incorrectly.
Both venomous and harmless reptiles have their place in nature and help balance vulnerable
ecosystems. Snakes assist farmers by controlling rats and mice – lizards help to control insects,
snails, etc.
It is dangerous to assume an apparently quiet venomous snake is, or can become tame. Many bites
have been caused by this assumption.
FACT SHEET No. 3
Reptiles are ectothermic and must obtain body heat from outside sources. Their optimum
temperature is around 30 degrees Celsius. In snakes, one lung is either atrophied or non-existent,
while the other is elongated, as are some of the internal organs. Some snake species have remnant
hip structure with atrophied leg bones. The more modern species have little or none of these
vestiges.
Reptiles evolved from labyrinthodont amphibians during the late carboniferous era and, by crossing the boundary
from aquatic to terrestrial life became the ancestral stock from which all terrestrial vertebrates have evolved,
both living and extinct.
Many changes and improvements were needed in the basic body plan to enable the transition to occur, some of
these being: skin sufficiently able to resist dehydration of essential body fluids, lungs and circulatory system
improved, a strengthened musculature and skeletal structure, larger brain and, perhaps the most innovative of all
- the land egg!
The origin of the snake (Ophidia) is a problem. From the anatomy of primitive snakes – boas, pythons and blind
snakes – it is obvious that they evolved from lizard ancestry (these species have remnant pelvic and leg bones)
but, the rarity of fossil remains from the Mesozoic (Dinosaur) era has prevented palaeontologists from
ascertaining the particular lizard species from which they evolved.
As there are many similarities in the skulls of Varanid monitors (Goannas) and snakes, it is theorised that when
transitional forms between lizards and snakes are discovered, they will be similar to lanthanotus, a primitive
short-legged, long bodied, burrowing varanid from Borneo. According to this theory, some of the early
transitional forms/snakes remained in their habitat, giving rise to the several families of burrowing blind snakes
that still exist, while other produced descendants that lived above the ground and sired pythons, boids and the
more progressive members of the group, the venomous snake.
Certain senses of snakes are quite unique. Pit Vipers, boas and pythons have evolved senses not present in other
vertebrates – heat sensitive organs (pits) that can pick up a change of temperature as little as .002 degrees
Celsius. These are used to detect the presence and position of camouflaged or nocturnal prey.
In the roof of the mouth is the Jacobson’s organ – tiny airborne particles are picked up the forked tongue and
transferred to this organ where they are tasted. Snakes are very good at tracking prey using this organ, and can
follow the faintest of scent trails.
Most snakes – with a few exceptions – have poor eyesight and are colour blind. When a snake wants to focus its
eyes on a subject, it has to make a conscious effort to do so. Snakes’ eyes don’t focus automatically like most
other animals.
The venomous snakes – especially the Vipers and Pit Vipers – have evolved the most advanced and specialised
fang structures of probably any known venomous animal although, their venom is nowhere near as potent as
that of the Elapids. The Elapids family comprises of snakes such as the Cobra family, Mambas, etc. with relatively
fixed fangs. All Australian venomous snakes are members of this (Elapid) family, even the ‘Death Adder’, a short,
thickset snake very similar in appearance and habit to the overseas vipers (hence the name ‘adder’). The venom
of Elapid snakes, unlike that of the Vipers, contains potent amounts of neurotoxins (nerve poisons) as well as the
tissue destroying toxins prevalent in Viper venom.
FACT SHEET No. 4
Research into the toxic components and actions of venoms is known as toxicology. Some of the major
toxins in Australian snake venoms and their biological effects on the human body are listed below:
Neurotoxins stop nerve transmissions at either the pre or post synaptic junctions of the motor endplate
region of the nerve. Without antivenin, death is inevitable as muscles can no longer contract, respiration ceases and
the brain and other vital centres fail, due to lack of oxygen. Most neurotoxins are also strongly myotoxic.
Myotoxins cause skeletal muscle damage and thereby the release of myoglobin – a muscle protein – that enters the
blood stream and becomes lodged in the kidney tubules. This causes kidney damage (acute tubular necrosis) and
renal failure (myoglobinuria). The process involving destruction of muscle fibre and excretion of myoglobin in the
urine is referred to as rhabdomyolysis. Myoglobinuria occurs slowly, and the resultant damage is irreversible.
Without antivenin, death is inevitable, and it can take the victim several days to die.
Cytotoxins destroy blood cells or the cells of most other tissue they come in contact with. They may
include cardio- toxins, myotoxins and rhabdomyolysis.
Heamotoxins destroy blood cells (haemolysis) and cause renal failure in the form of hamoglobinuria. An
anaemic condition may ensue in some victims with the urine appearing blood red from haemoglobin.
Coagulants cause blood to clot. Death may result from a clot in the main vein to the heart, while the
remaining blood fails to clot and internal haemorrhage may occur.
Anticoagulants affect clotting of the blood and can cause internal haemorrhage. Haematuria – blood in the
urine – causes the urine to turn red. Any wounds, cuts, etc., bleed continuously.
Hyaluronidase is often called the ‘spreading factor’, accelerating the movement and effects of the venom.
It dissolves the gel surrounding normal tissue, cells and fibres, speeding absorption of the venom.
Although the Australian elapids (fixed front fanged venomous snakes) lack the efficient folding fangs and
sophisticated venom delivery apparatus of the overseas Vipers and Pit Vipers, they have evolved in their
venom, some of the most potent toxins known. Eleven of our species produce venom more toxic than that of
the Indian Cobra, a species responsible for up to ten thousand human fatalities, each year in India alone and,
may be 50 to 100 times deadlier than the overseas Pit Vipers (eg rattlesnakes) and Vipers such as the deadly
Puff Adder of Africa. Why our snakes produce such toxins is not known and can only be speculated about.
Consider a species such as the Taipan, which with one bite could kill over 50,000 mice, 12,000 guinea pigs
or 50 humans. A possible reason for the development of such ‘overkill’ is specialised prey selection
involving either highly dangerous or greatly immune prey.
It should be realised that snakes evolved venom for the primary purpose of immobilisation and pre-digestion
of prey. Most Australian species would rather avoid any conflict with large animal (humans). This stands to
reason as it does the snake little good, if its enemy dies later from the effect of a bite it sustained, while it
was killing the snake! This is why snakes never attack humans and explains why hospital records show that
80% of bites are sustained by people either trying to kill or catch or otherwise interfere with the snake
involved. If envenomation does occur, the pressure immobilisation system will allow the victim to reach
medical assistance with minimal systemic effects.
10 THINGS YOU MAY
LIKE TO KNOW ABOUT SNAKES!!
1. Did you realise that only about ¼ of the world’s snakes are venomous and only about 200
species are dangerous to humans.
2. Australia is the only country in the world where most of its snakes (¾) are venomous.
3. Australia is the home of the top 8 most venomous snakes in the world and in fact, 18 of the
top 20 in the world live here.
4. Snakes are deaf and cannot hear airborne sounds at all.
5. Snakes are virtually blind and only have limited eyesight that can detect movement within 3
metres.
6. The fastest snake in the world can only travel about 12 kms per hour. Most able bodied
humans can sprint between 25 to 45 kms per hour. It is a myth that snakes can outrun humans.
7. Over the last 200 years most Australians who were bitten, were trying to kill the snakes they
encountered. Others were bitten by stepping on, chasing, teasing or trying to pick up snakes. In
nearly all of the bites, the snakes were only trying to defend themselves against a larger, attacking
animal.
8. FACT: any animal that is deaf and virtually blind and has no legs cannot chase people. It is a
myth that snakes chase people. It only takes an adult 3 or 4 steps to travel outside the range of
any snake’s vision.
9. FACT: snakes have no liking for milk – placing saucers of milk out to attract snakes, has no
effect on them. Snakes only drink water every couple of weeks.
10. FACT: it is not true that a snake will not die until the sun sets. They will die as soon as they
stop breathing from either natural causes or because they have been mortally wounded.
QUESTIONNAIRE
A. CONSERVATION
1.
2.
3.
4.
5.
Why should we conserve reptiles?
Are reptiles protected?
What prey animals do snakes usually feed on? How is this beneficial to us?
What prey do lizards feed on? And how is this beneficial to us?
Is there any penalty for the unnecessary killing of a reptile?
B. VENOMOUS SPECIES
1.
2.
3.
4.
5.
Approximately how many people are bitten by snakes each year?
State the two main reasons for 80% of snake bites.
What age group is known to be a high risk for snake and spider bite?
List the 3 most dangerous species in your locality?
What attracts snakes to human habitation?
C. ANTIVENIN AND ENVENOMATION
1.
2.
3.
4.
What system of the body transports the venom to the blood circulatory system and vital
centres?
What method of first aid should be used for snake bite, spider bite or other
envenomation?
How is antivenin produced?
Why should antivenin only be administered in a hospital, medical centre or by a doctor?
D. ADDITIONAL QUESTIONS
1.
2.
3.
4.
List 2 common non-venomous snakes in your locality?
Is there such a thing as a ‘tame’ snake?
Why do snakes constantly flick their tongues?
Australia hosts the five deadliest species of snakes in the world - list these.
Which, if any of these snakes are in your area?
5.
PLEASE COLOUR US IN …….
LEARNING TO LIVE WITH REPTILES: WORD PUZZLES
1.
Can you crack the secret code ?
V M E R L M N V M G Z O
Z D Z I V M V H H
.… ………… ……… … …………
… … ………… ……….
H G Z I G H
D R G S
N V.
.… ………… …
… ………
…… .
Code Breaker:
A B C D E F G H I
J K L M N O P Q R S T U V W X Y X
Z Y X W V U T S R Q P O N M L K J
I
H G F E D C B A
2. F ill in t he miss in g letters …. .
Tu rt l es l a y
E _ _ _
C ro co d i l es l i ve up
N _ _ _ _
S o m e s n ak es ar e
V _ _ _ _ _ _ _
S t u d yi n g rept i l es i s ver y
I _ _ _ _ _ _ _ _ _ _
S n ak es , l i z ards and crocodi l es a re
R _ _ _ _ _ _ _
C ro co d i l es l i ve t o be ver y
O _ _
An i m al s h u nt i ng at ni ght ar e
N_ _ _ _ _ _ _ _
R ep t i l e s k i n s are s h ed b y
M_ _ _ _ _ _ _
S n ak es an d ge ckos have no
E _ _ _ _ _ _
S n ak es b reat h e t hro ugh t hei r
N _ _ _ _
A rep t i l e wi t h fl i ppers i s a
T _ _ _ _ _
3. Fill in the missing words: Li z ards and s nakes a re (___ _____) t hat have
(_ _ _ _ _ ) s k i n . Thi s s ki n i s not (_____). The y (____) t hei r s k i n as t he y (____).
(_ _ _ _ _ _ _ ) m o v e b y wal ki ng. S n ak es m ove b y (__________) . Li z ards i n (_____ _ _ _ _ _ _ )
are n o t (_ _ _ _ _ ___ ). S om e (______) i n Aus t ral i a ar e (_____ ____).
But i f yo u p ra ct i s e c orrect (____ _____) yo u wi l l not (___) f rom t he (_____) bi t es .
Mi s s i n g w o rd s : pois onous , rept i l es , gro w, s cal y, Aus t ral i a, s nakes , venom ous ,
l i z ard s , s h ed , wri ggl i ng, di e, s l i m y, fi rs t ai d, s nake.