This document discusses snake anatomy and locomotion. It includes: - Descriptions of different modes of snake locomotion including lateral undulation, sidewinding, concertina, and rectilinear motion. - Details of snake anatomy like their flexible spine, belly scales that aid movement, and lung and heart structure adapted for breathing and circulation. - Studies on robotic snakes replicating lateral undulation and the importance of weight distribution and lifting during movement. - Features of snake circulation like cardiac shunts that allow mixing of oxygenated and deoxygenated blood, and how pythons have reduced shunting compared to other reptiles.

1. Safi Afzal
Reema Shamoon - PO
JelenaRadan – GL
RobieMoughni
LeikaRaychouni
Candace Babby

2. Safi
Locomotion on Land
o Lateral Undulation
o Sidewinding
o Concertina
o Rectilinear
o Slide-Pushing
http://science.howstuffworks.com/environmental/life/zoology/reptiles-
amphibians/snake3.htm

3. Safi
o Lateral Undulation
• Most common
• Waves of lateral
bending
• Scales push off
resistance points
o Sidewinding
• Surfaces with few
resistance points
• Diagonal path of
travel
• Fastest mode of
locomotion
http://www.cs.cmu.edu/~biorobotics/research/rsch_locomotion.html
http://www.sciencephoto.com/media/414095/enlarge

4. Safi
o Concertina
• Cycle of pulling and
straightening body
• Static friction is critical
• Narrow passages and
climbing
o Rectilinear
• Straight line
• Large snakes
• Belly scales
http://www.rubberbug.com/reptiles.htm

5. Safi
o Slide-Pushing
• Large undulations
• Snake tries to escape of smooth surface and
slips
• Very irregular, small movements
http://www.wildernesscollege.com/snake-tracks.html

6. Safi
o All snakes can swim
o Lateral undulation
o Highly aquatic snakes
o Semi-aquatic snakes
Pattishal A.&Cundall D. (2008) http://divehappy.com/indonesia/diving-gunung-api-volcano-of-the-sea-snakes/

7. Safi
o Genus Chrysopelea –
“Flying snakes”
o Dorsovental flattening
o Lateral undulation
o Generate lift
o Glide ratio similar to
other gliders
http://animals.nationalgeographic.com/an
imals/reptiles/flying-snake/

8. Reema
o Composed of
skull, vertebrae and
ribs
o Atlas (first vertebra)
o Ribs all along body are
NOT connected to
breastbone
o Creates flexibility
o Ability to move in S and
coil shapes.
http://www.blackdrago.com/science/anatomy_snake.htm

9. Reema
o Line bottom of snake
on its belly
o Creates agile mobility
o Work like a tire
gripping/treading a
surface
o Each belly scale is
attached to a rib and
muscle for optimal
control over
locomotion
http://ecx.images-amazon.com/images/I/41SwHhW%2BttL._AA300_.jpg

10. Reema
o Robotic snakes tested in lateral undulatory
movement with presence and absence of
resistance points
o Weight distribution changes during movement is
important
o Some snakes are able to lift their curves during
lateral undulation
• Loading (pressing down) and unloading (lifting)
• 35% increase in speed and 50% more energy efficient

11. Reema
In figure:
-A depicts a lifting snake in
action
-B & C are frictional force
distributions of nonlifting
and lifting snake
-Green arrows 
magnitude and
direction of force
-Red dots  snake’s
center of mass (also
resistance point)
-Black dots  inflection
points
-Red lines  place of
lift
http://www.ncbi.nlm.nih.gov/pmc/articl
es/PMC2700932/?tool=pmcentrez

12. Jelena
http://bio4120w12.pbworks.com/f/1333385454/snake-anatomy.gif

13. Jelena
AIR SAC
 (Madder, D)

14. Jelena
 (Clark , 1978)

15. Jelena
o Right Lung dominant – used respiration
o Left Lung Vestigial
• Trachea
• Bronchi
• Lungs
• Air sac
http://heat-pits.com.au/snake-anatomy-physiology/

16. Jelena
o The nostrils have valves that consist of a
specialized spongy tissue to keep water out
o Surface for
Air
http://api.ning.com/files/lsNu6og-q1Iwofk1aQ9n*1melLZ-
OT7gFqnSjOh2WWeiHsHZZGUDL2o4aW2V6AoQ043elbrZMJpZvOhTpdKK6dMFsSkxwa52/snake.jpg

17. Leika
o Five Chambered
Heart
• Two Atria
• One Ventricle
o Cavumpulmonale
o Cavum dorsal
• Cavumvenousum
• Cavumarteriosu
m
(Moyes& Schulte, 2008)

18. Leika
o Heart acts as two-circuit
pump:
Systemic Right Atrium
Cavumarteriosum Cavum
venous Cavumpumonale
Pulmonary Artery Left
Atrium Systemic
http://mycelular.org/reptile/reptile-body-systems.htm

19. Leika
o Ingest Large Prey
o Lack Diaphragm
• Pericardium-sac that encloses the heart.
http://arsanatomica.tumblr.com

20. Leika
(Lillywhite, 1988)

21. Candace
o Cardiac shunts within the heart of
the snake promote mixing of
oxygen-depleted blood and
oxygenated blood in different
directions.
o Pulmonary and Systemic
Circulation
• Blood Pressure is the same in systole
o Cardiac shunts occur because of
incompletely divided ventricles
o It also causes mixing of
deoxygenated and oxygenated
blood in ventricles.
o Cardiac shunts direct blood away
from its normal cycle. Hicks and Wang, 2004
Jensen et. al., 2010

22. Candace
o Relative resistance of the systemic and pulmonary
circuits regulates the blood flow distribution
between the arteries.
o Right-to-left Cardiac Shunt
• Blood that is recirculated within the systemic system
• Caused by a higher pulmonary arterial resistance
(constriction)
o Left-to-Right Cardiac Shunt
• Blood that is recirculated within the pulmonary system
• Caused by a reduced pulmonary vascular resistance
(relaxation)
Jensen et. al., 2010

23. Candace
o Python exhibits washoutshunts at the
cavumvenosum
• subdivided ventricle
• Cavumvenosum very small
• Unable to exhibit other shunts due to the shape of the
valve and its mechanisms
o Bulbuslamelle and Muscular Ridge
• Separation in early systole between cavumpulmonale and
cavumvenosum
• Causes the residual venous blood in the cavumvenosum
and arterial blood in the cavumarteriosum to be washed
out (from the shunt) into the aorta
• Low Residual volume and low cardiac output caused by
the washout shunt
Jensen et. al., 2010

24. Candace
o The amount of mixing between the arterial and
venous blood is reduced in the python.
o Cardiac shunts are decreased in magnitude in
comparison to other reptiles
o Indicated by the flow of blood which has the ability
to remain separate during the cardiac cycle.
o Oxygen levels in arteries remain increased
• During digestion, the systemic venous oxygen
concentrations are reduced.
o Pythons have the capability to produce high
systemic blood pressure with low pulmonary blood
pressure.
Jensen et. al., 2010

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