Locomotor endurance and oxygen consumption of harvestmen

Animal movements are highly constrained by morphology and energetics. In addition, predictable bodily damage can constrain locomotion even further. For example, for animals moving on land, losing legs may impose additional costs. We tested if losing legs affects the distance travelled over time (endurance) and the metabolic costs of locomotion (oxygen consumption) in Nelima paessleri harvestmen. These arachnids voluntary releases legs (i.e., autotomy) in response to predation attempts. We used flow-through respirometry as animals moved on a treadmill inside a sealed chamber. We found that endurance decreased gradually with an increasing number of legs lost. Interestingly, oxygen consumption increased only for harvestmen that lost three legs, but not for individuals that lost only a single leg. These results have different ecological and evolutionary implications. Reduced endurance may impair an animal’s ability to continue moving away from potential predators, while increased oxygen con...