Meeting Abstract

89.3  Sunday, Jan. 6  Terrestrial Locomotor Mimicry at the Kinematic Level: Does the ant-mimicking jumping spider Myrmarachne formicaria walk like an ant? SHAMBLE, P.S.*; BEATUS, T.; COHEN, I.; HOY, R.; Cornell University; Cornell University; Cornell University; Cornell University pss92@cornell.edu

Most studies of mimicry have focused on phenotypically static traits, such as color pattern and body shape. However, new research–to which this work contributes–suggests that behavior and motion are highly important in enhancing likeness between mimics and models. Our work examines locomotory mimicry, involving a jumping spider (Myrmarachne formicara) that has a striking resemblance to ants. This species is a convincing morphologically visual, static mimic, but it is also widely-believed to walk like an ant. It solves the 8 legs (spider) vs. 6 (ant) problem by waving its forelegs like antennae, “functionally reduc[ing] the number of legs in the mimic from four pairs to three” (Cushing 1997). How good is the mimicry when set in motion? Our research is the first to reconstruct M. formicaria’s actual gait. We used high-speed video to reconstruct the spider’s limb movements in 3D. Our results show that M. formicaria actually break their motion into two parts: 1. a mobile phase in which they walk with an eight-legged jumping spider gait; 2. a stationary phase in which they mimic ants by elevating their forelegs. We conclude that the timing of these distinct locomotive phases–combined with aspects of the spider’s static appearance–are responsible for creating the illusion of “ant-ness.” Our findings reinforce the need for researchers to consider behavior and motion in studies of mimicry systems.