Description

Many invertebrates are capable of jumping, such as locusts, fleas, mantids, and cockroaches. Some invertebrates can jump without the use of their legs, such as click beetles and springtails (Mo et al., 2020). Nematodes, which are non-segmented roundworms, are capable of a variety of complex behaviors, though jumping is arguably the most visually striking. Jumping is a rare behavior among nematodes, with only a few species in the genus Steinernema being reported as capable of jumping (Campbell and Kaya, 1999). The kinematic performance of S. carpocapsae jumping was first described in 1999, with the peak velocity and peak acceleration reported as 1.13 m/s and 164 g, respectively (Campbell and Kaya, 1999). These data were not calculated based on direct observation and high-speed videography, but were estimated based on the distance, height, and timing of the nematode jumps. This nematode is reported to be capable of jumping a distance of 4.8 mm, and a height of 3.9 mm (Campbell and Kaya, 1999).

We investigated the kinematics of Steinernema carpocapsae jumping behavior using high-speed videography (Videos 1 & 2). We calculated peak velocity to be 1.9 m/s and peak acceleration to be 38205 m/s² (3899 g), based on measurements from jumping sequences filmed at 20 kHz and using the average infective juvenile length of 558 µm (Nguyen et al., 2007) (Video 2). The velocity calculated here is one and a half times greater and the acceleration is more than twenty times greater than what has been previously reported for S. carpocapsae jumping (Campbell and Kaya, 1999). The jumping acceleration of S. carpocapsae is significantly greater than fleas, click beetles, or any other jumping animal for which acceleration has been reported. These measurements are likely underestimates of both peak velocity and acceleration, as the jumping sequence probably needs to be recorded at 50 kHz or greater and captured from multiple angles to get more accurate measurements (deVries et al., 2012).