Our present research is comparing the physics involved in prey capture between the moth-specialist spider family, Cyrtarachninae, and classic orb-webs. We serve to understand the material properties of the glues and the threads through the analysis of high-speed video kinematics.
Here we have the bolas spider, Mastaphora hutchinsoni. It uses pheremones to attract male moths, then throws a bolas at it. This bolas is a sticky ball of glue which attachs to the moth, adhering to it instantly.
We use high-speed video to track the path of the spider and moth, using physics to figure the forces and speed involved in prey capture.
We are interested in studying the evolution of specialized predatory behaviors and the biomechanical systems that make those behaviors possible. One of the things I find most amazing about spiders is their ability to adapt to nearly every climate and ecosystem on earth. Spiders are extremely diverse organisms with many unique adaptations to survive in the most unusual places. Each species is capable of producing multiple types of silk, each with unique material properties. Different lineages of spiders use this silk for many purposes, such as making egg sacs, building homes, and my favorite, catching prey. The classic wagon wheel design of the orb-web is made up of 5 different silk types!
The material properties of spider silk have evolved to aid in their survival. They have also been evolved to be optimized with their natural environment. Many materials, spider silk glue in particular, are responsive to humidity and temperature. This makes proper testing of these materials, through recreation of natural conditions, difficult in the lab. It can also be especially difficult to trigger spiders to make webs in the lab because they wait for specific environmental cues! To solve this problem, we bring the lab to the spiders!
Ecomechanics/Ecophysiology
Breakdown of Bolas Spider Prey Capture Event. Distance between Spider and Moth (cm) over time are labeled to show the separate phases of prey capture. Phases (P) in the graph are correlated with video images on the right; P1 – Observation, P2 - Bolas Creation and Swing, P3 – Falling, P4 – Reeling, P5 - Submission. You can see a movement as the moth hovers near the spider before getting caught; it then drops and is subsequently pulled in. If the moth is still thrashing, there is a prolonged flattened area where the spider handles the moth until it is controlled. Slopes of phase 3 line can used to calculate the falling speed of the moth! We can compare this to orb-webs to determine the behavior and material properties involved in prey specialization!
Mastophora hutchinsoni prey capture. This bolas spider waits for the moth to get close then throws it bolas and catches it in a single swing.
Cladomelea akermani prey capture. This bolas spider spins constantly in hopes it will hit a moth flying by. Here you can see the tracked path of the spiders spinning arm and bolas. We can use those points to calculate the physics of the system and the material properties of the spider silk.
Animal Husbandry
In our lab, we collect local spiders and keep them in our greenhouse. There they can live a stress-free life with an unlimited supply of crickets to eat; we only ask for some silk in return. When spiders make egg sacs we put them back in nature.
We work tireless to give spiders the best home we can, with cages customized to allow maximum comfort for our various species. At present we have housed, numerous species of orb-weaver (on the right, Argiope), Japanese moth-specialists, Cyrtarachne, and Kentucky native Bolas spiders (on the left, Mastaphora). We raise moths specifically to feed these spiders.
We hope students will learn about the dynamic nature of ecosystems through animal husbandry and our late-night spider hunts in the woods. Our spider hunts also include daytime trips, searching through dense flowers on the Vassar nature Preserve. We hope to have students conduct experiments altering lab environmental conditions to maximum spider web production and health while in captivity.