Question

Which is the correct representation of the posture of a house lizard as it climbs a wall? 

• A. A
• B. B
• C. C
• D. D

Hint:

When analyzing animal movement, think about stability. The animal's center of gravity must always be supported by the limbs on the ground. A contralateral walking pattern is the most common way for quadrupeds to achieve this.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept: 
This question tests knowledge of animal locomotion, specifically how a quadruped (four-legged animal) like a lizard moves while climbing. The key principle is maintaining balance and continuous forward motion. 
Step 2: Key Formula or Approach: 
Many four-legged animals use a contralateral gait for walking, trotting, and climbing. Contralateral means that limbs on opposite sides of the body move in conjunction. Specifically, the front left leg moves with the rear right leg, and the front right leg moves with the rear left leg. This pattern ensures that the animal always has a stable base of support (usually three limbs on the surface at any given time), preventing it from falling. 
Step 3: Detailed Explanation: 
Let's analyze the limb positions in each option: 
(A): The left front and left hind limbs are lifted, while the right limbs are on the ground. This is an ipsilateral gait (same-side limbs move together). This is highly unstable and not used for climbing. 
(B): The right front and right hind limbs are forward. This is also an unstable ipsilateral posture. 
(C): The right front limb and the left hind limb are forward, while the left front and right hind limbs are back, providing support. This is a perfect example of the stable contralateral gait. The lizard is balanced and in a position to propel itself forward. 
(D): The posture is unnatural. The hind limbs are splayed too far out, and the front limbs are not positioned for effective forward movement. This posture lacks stability and power for climbing. 
Step 4: Final Answer: 
The correct representation of a lizard's climbing posture, which uses a stable contralateral gait, is shown in option (C).