t14 locomotion wrksht.ppt - clark university

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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


� __________

� ______________

� ______________

� ______________

Photos © J & C Sohns, S Zankl



� ________________

� Crawling/slithering

� Enhancing stride length

Photos © T Laman, PJB


� ______________

� 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


� 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?


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


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� Fulcrum

� In-lever

� Out-lever

More on lever

systems


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


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� 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


� Many locomotor specializations of limbs exist

� ___________________________ in Varanus exanthematicus

� Enhances stride length

� Leads to higher velocity



� _____________ 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


� 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


� ____________________

� 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


� 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


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


� 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


Crotalus cerastes


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


� 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


� 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


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

t14 locomotion wrksht.ppt - clark university

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