- #1
- 2,535
- 10,242
Some spiders are known to fly on the breezes by extruding silk strands (like web material) from their abdomen. This is commonly thought to be caught in the wind and carry them away. This would explain the occasional spider you might see drifting by when you are outside.
Many (including that shrewd observer of nature, Charles Darwin, in the 1830's) were not convinced this provided a full explanation.
It is now reported that by making use of the planets Earth's electric field (ground (-) vs. surrounding (+)), of 100 V/m (I'm surprised at the size of this, but I guess air has low conductivity (unless ionized)).
They can sense this by changes in how little hairs on their legs respond to electric field.
Insects have lot of hairs that are innervated at their base, and detect movement of air over the surface of the body. This is information that can be used for many different purposes, flight control, wind detection, air movement from local objects, resonating to particular sounds. (Some detector hairs can be specialized for particular purposes.) Other kinds of hairs may have chemical detectors (smell/taste).
The negatively (-) charged silk strands the spider extrudes will naturally go in the positive direction (up). Getting the process started, and providing at least some upward force.
NY Times video (its very good) and article on the aerodynamics of spider flying, but voltage not considered.
Short article on electrical aspects in "The Atlantic".
Many (including that shrewd observer of nature, Charles Darwin, in the 1830's) were not convinced this provided a full explanation.
It is now reported that by making use of the planets Earth's electric field (ground (-) vs. surrounding (+)), of 100 V/m (I'm surprised at the size of this, but I guess air has low conductivity (unless ionized)).
They can sense this by changes in how little hairs on their legs respond to electric field.
Insects have lot of hairs that are innervated at their base, and detect movement of air over the surface of the body. This is information that can be used for many different purposes, flight control, wind detection, air movement from local objects, resonating to particular sounds. (Some detector hairs can be specialized for particular purposes.) Other kinds of hairs may have chemical detectors (smell/taste).
The negatively (-) charged silk strands the spider extrudes will naturally go in the positive direction (up). Getting the process started, and providing at least some upward force.
NY Times video (its very good) and article on the aerodynamics of spider flying, but voltage not considered.
Short article on electrical aspects in "The Atlantic".