Animal Design

Question 1

Describe how bipedal and quadrupedal animals are adapted for posture and movement.

Answer 1

Bipeds-
- Strong spinal muscles for stability/posture
- Free thoracic (fore)limbs for various functions (eg: flight, carrying food, tool usage)
- Long, columnar hindlegs for walking with an upright spine - COM directly above base for stability
- Long hindlegs with large proximal muscles & long tendons (catapults) for jumping (levers) with a crouched posture to create more jumping power
- Limbs/feet can be adapted for perching or catching prey or wings for flying

Quadrupeds-
- Large base of support of COM for high stability
- Fore/hindlimbs can differentiate function - forelimbs = turning & support / hindlimbs = speed & power
- Carnivores have angular hindlimbs for unsteady locomotion

Question 2

Explain major similarities and differences in body form between bipeds and quadrupeds.

Answer 2

Similarities-
- Can differentiate fore/hindlimb functions for various needs
- Adapted to be most energy efficient
- Conserve energy through using tendons

Differences-
- Quadrupeds have a large base of support to give higher stability of COM
- Quadrupeds built for speed/endurance - eg: decreased weight in distal limbs
- Quadrupeds are digitigrade/unguligrade
- Bipeds COM is directly above base
- Bipeds have longer hindlimbs than forelimbs for jumping
- Bipeds are plantigrade

Question 3

Discuss anatomical adaptations of animals for specific functions.

Answer 3

• Quadrupedal = spreads COM to increase stability
• Fore/hindlimbs can differentiate functions for efficiency in movement
  -Tendons have a spring-like action as they stretch and recoil to save energy
• Tendons act as catapults as they store energy slowly and release energy quickly to amplify power
• Distal limbs have reducing digits to conserve energy as the limbs are lighter, allowing more economical and efficient movement
• Muscle replaced by tendons for lighter distal limbs
• Long forelimbs allow for brachiation - provides a long lever to move themselves through the trees

Question 4

Propose and justify adaptations for function in a range of extant, extinct and imaginary species.

Answer 4

• Increasing size of the animal, decreases the amount of muscle force due to a smaller muscle area : muscle volume ratio - therefore, larger animals have a more upright posture to allow the GRF to travel straight through the limbs to conserve energy (though reducing their gait)
• Predators have angular limbs, bare weight on their digit and have claws for unsteady locomotion (acceleration/deceleration)
• Prey have reducing distal digits and replace muscle with tendons to make themselves lighter and more efficient with their movement