Friday, February 09, 2007

Biological Gyroscopes

Another short post today - and from another story found on the BBC - on the discovery of a gyroscope-like mechanism in moths to aid in the maintenance of in-flight balance.

As is well known, moths are most active at night, or at least during those periods of the day (or rather, night) which have the lowest levels of light. As such, when in flight, it would be near impossible for them to use visual landmarks as a reference for the purpose of stabilisation. So, how is this in-flight stabilisation achieved? According to Sane et al (Published in Science magazine, vol 315, p735), moths have what is in effect a gyroscopic system in their heads. The mechanism works roughly as follows: using an organ in their heads (Johnston's organ), the moths are able to detect their body position in relation to their antennae position, which apparently remains stationary during flight, thus providing what is in effect a fixed reference point. This was demonstrated by removing the antennae, resulting in the moths displaying very irregular flight patterns, bumping into walls and flying backwards. By merely 'glueing' the antennae back on, normal flight behaviour resumed. A somewhat cruel but very effective demonstration.

Coming from my point of view, I think this is an elegant example of how the morphology of an agent has an effect on behaviour, even if the required sensory system is in place. Thus here, the sensor (Johnston's organ) does not contribute adequately to overall agent behaviour if the body shape (antennae) is wrong - thus demonstrating the importance of not only a well designed control system, but also the correct type of physical implementation which complements this control system. So essentially, embodiment a necessity, not an extra.

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