1.2 Animal Design Flashcards
What are some selection pressures that may influence evolution for locomotion?
Resources - habitat, food, mates
Environment - temperature, weather, access (geography)
Biological - predators, pathogens (disease)
What does a locomotor system need to do?
Support body mass
Move COM
Move limbs
- all of which consume energy
What is self-propelled movement?
Not by fluid movement, needs limbs that allow it to deform and interact with the environment
What do selection pressures dictate?
Animals needs to move:
- on different substrates
- in more that one direction
- at varying speeds
All whilst using minimum energy
Why is a quadruped stance more favourable?
Large base of support = stability
can differentiate function between limbs
(synergistic - forelimbs essential to manoeuvre, hindlimbs essential for powering)
Why is a bipedal stance more favourable?
Free thoracic limb for other functions
- however, have no left-right differentiation in any meaningful way
Define gait
@ simplest level gait = lifting up the limb, extending it forward, putting it on the ground and pulling it back
How does muscle anatomy influence locomotion?
Size & morphology Internal architecture Muscle attachment Fibre type Muscle firing patterns - timing potentially produces a more efficient gait
What is pennate muscle?
Attaches at an angle to the tendon
- can produce substantially more force because muscle has more cells in cross-section
What are the three functions of tendons?
Springs - stretchy tendon in series with muscle, muscle-tendon-bone = spring
Catapults - don’t store energy to increase efficiency but to increase scale of jump or movement
Control - both beneficial and a cost, muscle and tendon so a little less control as far as general precision of positioning
General principles of Bipedal: walking design
Long columnar hindlegs
Shorter forelimbs freed up for tool use/carrying
Plantigrade - foot as a lever
Upright spine - centre of mass directly above base of support
General principles of Bipedal: Jumping design
Long legs and long distal levers beneficial
Musculature to maximise force, contraction speed, series of compliance (use of long tendons)
General principles of Bipedal: Flight design
Limbs and feet adapted for perching (body weight support) and catching prey
Forelimbs adapted as wings - for flapping, hovering or gliding flight
What are pros of lightening the distal limb?
Allows lengthening of the limb
Taller and longer strides
Reduces the mass
What are cons of lightening the distal limb?
Higher stresses, increased forces over a smaller area = higher incidence of injury
