CAN SIMPLE EXPERIMENTAL ELECTRONICS SIMULATE THE DISPERSAL PHASE OF SPIDER BALLOONERS?

Here we describe the structure of a fall speed chamber designed to measure, with low experimental error, the terminal velocities (fall speeds) of spiders of known weight and a given length of silk. We also describe the construction of a simulated individual (SI) which could later be used to estimate the distance travelled by ballooning spiders in the field. Our data and analysis suggest that Oedothorax spp. (Linyphiidae) and Pachygnatha degeeri (Tetragnathidae) individuals have fall speeds that can be described by their silk length and mass. Of the observed deviance in the fall speeds, 73.7% could be explained by a GLM model common to both species groups. Overlaying the SI fall speed data on this GLM surface suggests that the SIs have similar fall speed behaviors to spiders. However, further estimation is necessary before SIs could be considered valid models for evaluating spider ballooning distances.