Meeting Abstract
In feeding systems, jaw opening and closing may involve both muscle contractions and the stretch and recoil action of elastic structures including tendons and ligaments. The contribution of these elements may vary, both with changes in behavior and temperature. Muscles are less capable at extreme temperatures due to enzymes being less functional, which follows the Q10 principle. However, the action of elastic systems is supposedly temperature insensitive. The goals of this study were to use temperature manipulations during axolotl feeding to determine if feeding behaviors involve elastic recoil, and also to determine whether or not the contribution of elastic structures varies among behaviors, specifically strikes and chews. High-speed recordings were taken of seven axolotls feeding on crickets at low (6°C), intermediate (14°C), and high (23°C) temperature. We extracted gape opening and closing speeds for each behavior and temperature treatment. We found that gape opening speed for strikes increases with temperature, but the closing speed for strikes is unaffected by temperature. These data indicate that gape opening during strikes is largely muscle controlled, whereas gape closing during strikes is elastic recoil driven. During chewing, both gape opening and closing speed decreases as temperature increases. We cannot fully explain this result, but hypothesize that at low temperatures, the muscles involved are nearly incapacitated, leaving only elastic recoil to drive the behavior. As the animal warms, the muscles can function, and actually slow the entire process down. These data add to a surprisingly small body of evidence of elastic recoil action in vertebrate feeding systems.
