Reference
Glossary
Definitions stay short, testable, and consistent across the site. Terms will expand as new articles introduce more detail.
- Surface tension
- Energy required to increase a liquid surface area. Governs how much force is needed to deform the air-water interface under a spider's leg.
- Contact angle
- Angle where liquid, solid, and air meet. Large angles indicate hydrophobicity; advancing vs. receding angles show hysteresis.
- Capillary length
- Length scale where gravity and surface tension balance. If a leg contact area stays below this, it can float without sinking.
- Setae
- Microscopic hair-like structures on spider legs that trap air pockets and reduce wettability.
- Marangoni effect
- Flow driven by surface tension gradients. Relevant when secretions or contaminants change the interface near a moving spider.
- Drag
- Resistance force from water or air on a moving object. Influences stride frequency and energy expenditure on the surface.
- Hydrophobicity
- Property of repelling water, often measured via contact angles or roll-off angles on a coated surface.
- Biomimetic
- Design approach that imitates biological strategies; in this case, spider locomotion and wetting control.
- Weber number
- Dimensionless ratio of inertia to surface tension (rho * U**2 * L / gamma) that flags when impacts risk splashing or puncturing the interface.
- Bond number
- Dimensionless ratio of gravity to surface tension (rho * g * L**2 / gamma); staying below one keeps the body supported by capillary forces.
- Plastron
- Persistent air layer held between hydrophobic microstructures; on spider legs it cushions impacts and enables limited gas exchange.
- Capillary wave
- Surface wave governed by surface tension; stride timing often avoids constructive interference of these ripples.
Need more depth? Articles will link back here, but we can also add equations or contextual notes if repeated across posts. Suggest additions through the methodology page once collaboration opens.