Bolas: lure, flick, and adhere
See how chemical attraction, active movement, and deformable glue combine, then test a passive pendulum analogy.
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Original WebTug explanation with animated teaching diagrams and credited still photographs. On-screen text carries the lesson; there is no audio narration.
Diagrams simplify the science. Animation timing and diagram dimensions are illustrative, not measurements of live spiders.
Compare bolas line length →Read the full transcript
- A capture device on one line
This still photograph introduces Mastophora hutchinsoni. Hunting females use a silk line ending in an adhesive droplet: the bolas.
- Bring the target within reach
The spider releases chemical signals resembling female moth pheromones. Male moths approach, bringing a flying target close to the sticky droplet.
- The spider supplies the flick
An active leg movement sends the bolas toward the moth. The line and droplet stretch as the capture device accelerates.
- The glue changes shape
During contact, the adhesive spreads into the moth's scales. The deformable droplet and silk help manage the struggling prey's motion.
- Simplify one part of the motion
Our lab uses a passive pendulum baseline. It leaves out active flicking, chemical attraction, silk extension, and glue deformation.
- Which line swings more slowly?
Keep swing energy and loss fixed. Compare short and long lines; count swings over the same interval before explaining your prediction.
Scientific sources and media credits
Mastophora hutchinsoni — Mastophora hutchinsoni ♀ (48448404301).jpg by Christina Butler, CC BY 2.0. Photograph fitted within the video without changing its composition; labels and animated diagrams added around it.
Script, diagrams, animation, and editing: WebTug, September 27, 2026. This video adaptation is available under CC BY-SA 4.0; individual photographs retain their credited licenses.
What the game helps you notice
A bolas spider flicks a silk line with an adhesive droplet toward prey. This timing game uses an ideal pendulum: line length affects its period, while the sticky tip provides the contact point.
What does a longer pendulum line change?
Its natural swing takes longer: in the small-angle model, period is proportional to the square root of line length.
The repeating swing and prescribed moth path are practice patterns. Real strikes are actively driven, and stretching silk and deforming glue are more complex than a rigid pendulum.
Try this experiment: Which line takes longer to swing?
Keep swing energy and swing loss unchanged. Compare a short line and a long line, and count swings over the same interval.
Open this experiment and compare A / B →Meet Mastophora hutchinsoni and explore its research, then use the return link to play again. The challenge scores are game feedback, not measurements of your scientific understanding.
Primary research: Diaz and Long, Insects (2022)