T14 Locomotion wrksht.ppt - Clark University
Transcript of T14 Locomotion wrksht.ppt - Clark University
8/19/2013
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Topic 14: Body support & locomotion
� What are components of locomotion?� What structures are used for locomotion?� How does locomotion happen?
� Forces� Lever systems
� What is the difference between performance and kinematics?
� What are the various modes of locomotion?� In water� On land� In the air
What structures are used for locomotion?
� Structures for locomotion
� ___________
� Walking/running
� ____________
� Digging
� ____________
Photos © PJB, National Geographic, G Nafiz, KP Bergmann
� Structures for locomotion
� __________
� ______________
� ______________
� ______________
Photos © J & C Sohns, S Zankl
What structures are used for locomotion?
� Structures for locomotion
� ________________
� Crawling/slithering
� Enhancing stride length
Photos © T Laman, PJB
What structures are used for locomotion?
� ______________
� Gliding
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How does locomotion happen?
� Newton’s three laws� 1: A body in motion will
remain in motion unless a force acts on it & vice versa
� 2: Force = mass x acceleration
� F = ma
� 3: For every action there is an equal and opposite reaction
� Locomotion is the result of the ___________________ ______________________ ______________________
� This occurs with all substrates and in many situations
© JF Alward
� Forces produced during locomotion� Animal’s muscles exert a force F on substrate
� Substrate exerts a reaction force, R, equal & opposite to F
� R is often called a “_________ _________________”
� R can be broken down into:
� P – Forward _____________ component
� V – Vertical component opposite to ______________
� L – _______________ components also exist
Pough et al. 2004, Fig 10-1
R
F
P
V
L
How does locomotion happen?
� Lever systems
� A lever is a rigid bar that
pivots about a fulcrum
� Each lever has 2 lever arms
� ______________, length Li� ______________, length Lo
� Each lever arm has a force associated with it
� _______________, Fi� _______________, Fo
� Force is exerted on the in-
lever, and produced at the
out-lever
� Fi x Li = Fo x Lo
Pough et al. 2004, Fig 10-3b
• Same in-force
• Same in-lever + out-lever
• What do the diagrams below tell us?
How does locomotion happen?
Fi Fi
Li LoLi Lo
More on lever
systems
� Classified by relative position of parts
� 1st Class: Fulcrum between in & out lever
� 2nd Class: Out-lever in the middle
� 3rd Class: In-lever in the middle
Pough et al. 2004, Fig 10-3
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� Fulcrum
� In-lever
� Out-lever
More on lever
systems
Pough et al. 2004, Fig 10-3
A
C
B
D
E
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How are performance & kinematics different?
� _________________
� A measure of how good something is at doing something
� In locomotion, there are several measures of performance
� _______________
� Sprint speed
� _______________
� Power output
DJ Irschick Plot: Irschick & Jayne 1999; Diagram: PJB
� ________________
� A measure of how something is done
� In locomotion:
� _______________
� Stride frequency
� _______________
� Limb angles
� _______________
� Can be very detailed
� Kinematics and performance are related
� Sprint speed = stride length X stride frequency
� Morphology can be closely related to kinematics
� Hind limb length in lizards is proportional to stride length
How are performance &
kinematics different?
What are the various
modes of locomotion?
� Aquatic: _________________
� Used by elongate herps
� Serpentes, Gymnophiona, Sirenidae, Amphiumidae
� Many strong swimmers are not that elongate
� Iguana, Amblyrhychus, Basiliscus, Physignathus,
Crocodylia
� Involves the body and tail
� If limbs are present, they are folded back against body
� Undulations increase in _________________ caudally
Photo © T De Roy; Pough et al. 2004, Fig 10-17
Modes of locomotion
� Aquatic: __________________� Anura
� Simultaneous ____________ with hind limbs
� Body is held rigid
� Each propulsive kick counteracts drag from the water
� Testudines
� Trionychidae: ____________ ______________ with all four webbed limbs
� Cheloniidae: Simultaneous ____________ of flippers
� Lift and propulsion generated with up & down stroke of front limbs
� Steer with hind limbs
Pough et al. 2004, Fig 10-19, Photos: ??
Modes of locomotion
� Terrestrial
� Most terrestrial locomotion involves ____________
� Many exceptions
� In general Amphibia and “Reptiles” have a __________ _____________
� Limbs oriented laterally as opposed to parasagittally
(like mammals)
� Crocodylia and Chamaeleonidae have a more erect posture
Photos © PJB, KP Bergmann, A Britton
Terrestrial locomotion
� ___________� There are many ways to determine gait
� Generally include
� Sequence of foot falls
� Number of limbs in contact with the ground (min & max)
� Relative speed
� Limbs have more air time with ____________________
� Running animals often have no contact with the ground at some point in stride cycle
Pough et al. 2004, Fig 10-2
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Terrestrial locomotion
� Gaits are often poorly defined in sprawling vertebrates
� Crocodylus johnstoni
� Can ______________
� More upright posture
� Often only two feet on the ground
� ______________ is an asymmetrical gait
© A Britton
Terrestrial locomotion
� Many locomotor specializations of limbs exist
� ___________________________ in Varanus exanthematicus
� Enhances stride length
� Leads to higher velocity
Pough et al. 2004, Fig 10-5
Terrestrial locomotion
� _____________ and high speed
� Bipedal lizards tend to have:
� Long ________________
� Muscles proximally on hind
limbs: Speed vs. Force
� Short front limbs
� Long tails (counterbalance)
� Bipedalism is associated with high speed in lizards
� May be ___________________ high speed
� Even non-bipedal lizards sometimes run bipedally
Irschick and Jayne 1999
Terrestrial locomotion
� Some high speed species move on fluid substrates
� ____________: Basiliscus
� ____________: Uma, Callisaurus
� Often additional adaptations for this:
� Toe fringes on posterior edge of toe
Photos: ??, KE Bonine, PJB
Terrestrial locomotion
� ____________________
� Anura, lizards
� Specializations (mainly Anura)
� Rigid, light body
� Long hind limbs
� Short, rounded ilium
� Allows rotation of body to control jumping angle
� Competing aspects of a good jump
� ____________________� _________________________
� _________________________
� _____________________
� Increased weight decreases velocity, distance and height
Toro et al. 2004; © National Geographic
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Modes of locomotion
� Jumping
� Tail plays a _________________ role in lizard jumping
� Anolis carolinensis
Gillis et al. 2009
Terrestrial locomotion
� Limbless locomotion
� The body axis is responsible for pushing on substrate
� Involves complex musculature, with some muscles crossing multiple joints in snakes
� Simpler set of muscles in lizards
Pough et al. 2004, Fig 10-17
Limbless locomotion
� Limbless lizards and snakes move differently
� Limbless lizards all use simple undulation
� Snakes have a large repertoire of modes of movement
� _______________________
� _______________________
� _______________________
� _______________________
� _______________________
Photo © PJB
Limbless locomotion
Pough et al. 2004, Fig 10-11, 10-12
Fobject
Fobject
Flateral
Flateral
Fforward
Fforward� Lateral undulation� Horizontal waves travel down
body
� ___________________ objects in the environment
� Posterior and lateral force components
� Slide-pushing� Similar to lateral undulation,
but:
� ______________________ ______________________
� Very fast undulations
Limbless locomotion
� Rectilinear locomotion
� Involves bilateral waves of ______________________
� Costocutaneous muscles move skin relative to body wall
Pough et al. 2004, Fig 10-15
� Movement is in a straight line
� Can see waves of muscle contraction along body
Limbless locomotion
� Concertina
� Slow, energetically expensive
� Localized body bends are made and then straightened
� Use in ___________________ _________________________
PJB; Pough et al. 2004, Fig 10-13
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Limbless locomotion
� Sidewinding
� Specialized locomotion for:
� _______________________
� _______________________
� Snake pushes vertically down on substrate
� Sections of the body are:
� Lifted
� Moved forward
� Placed back down
� Generally only two points of contact with substrate
Pough et al. 2004, Fig 10-14
Crotalus cerastes
Terrestrial locomotion
Pough et al. 2004, Fig 10-21, www. Digimorph.org
� Fossorial specializations
� Limblessness
� Often involves structures to force way through substrate
� __________________ in Bipes with front limbs
� Amphisbaenia have a skull that can be used for digging
Terrestrial locomotion
� Fossoriality
� ____________________
� Skin can move relative to the body
� Body can thin or thicken to burrow
� Pointed skull drives through
substrate
� ____________________
� Undulations under a loose substrate
� Limbs folded along body
� Often used as a defense to
escape from a predator
PJB; Pough et al. 2004, Fig 10-20
Terrestrial locomotion
� Clinging
� Claws
� _____________________
� Gekkonidae, Diplodactylidae, Anolis, Prasinohaema
� Involves elaborations of scales
called setae (seta)
� Adhesion by intermolecular forces: van der Waals forces
� _____________________
� Many Anura
� Have adhesive discs on digits
� Capillary adhesion
� Water on the structure is needed
Pough et al. 2004, Fig 10-25; KP Bergmann
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Aerial locomotion
� No amphibians or “reptiles” have powered flight
� ___________________________� Involves jumping off a high place and spreading of patagia
� Difference between falling, parachuting and gliding is the amount of LIFTrelative to DRAG
� The more lift, the lower the angle of descent, the more “gliding” the descent is
Pough et al. 2004, Fig 10-27
Aerial locomotion
� Gliding has evolved several times independently in Borneo
� Distance between trees > in many other parts of the world
Photos © T Laman
Chrysopelea, Draco, Rhacophorus, Ptychozoon