Which of the following is NOT a described feature of the stay apparatus?

• A. It stabilizes limbs in standing position
• B. It is a passive automatic system
• C. It prevents fatigue in muscles by reducing energy requirements
• D. It increases energy expenditure

Answer: (D)

The stay apparatus is a passive, automatic system that mechanically locks the joints to keep the limbs steady in the standing position. It relies on ligaments, tendons, and joint structures to maintain posture without requiring continuous muscle contraction, so the animal can stand with minimal muscular effort. This setup reduces energy expenditure and helps prevent fatigue because the muscles aren’t doing sustained work to hold the body up. Therefore, describing it as increasing energy expenditure would be inaccurate, since the stay apparatus is characterized by conserving energy rather than using more.