Saturday, April 3, 2010

Decentralization:The power of many: Honey Bees : Foraging

This post explore "Food Foraging Problem" faced by honey bees. Honey Bees covers around 14 km of area around their colony to search for honey. There are around 45k bees average in a colony, where subsection of them goes for discovery of food and foraging. To make one pound of honey, workers in a hive fly 55,000 miles and tap two million flowers! To tap millions of flower, located randomly within the region, it is waste of energy of all the bees start searching food. To conserve energy, only few called scout bees search for location of food and pass the location to other fees. Well this is amazing form of efficiency with no single coordinator.

I will try to dive deep into this problem. I will divide the foraging problem into two parts, environment specific and honey bees specific.

Environment Specific: Environment consists of an avg. area of 14km around the beehive. Honey is found as nectar in flowers and flowers have limited lifespan and source of nectar. Environment has other competitors and hostile conditions (with urbanization in place).

So everything boils down "being at the right place, at the right time and having good luck"

Honey Bees Specific:
  1. How do they distribute themselves the searching area? Do they search randomly or they follow some pattern? Remember if everyone starts searching food, there will be repetitions and bees will consume more energy on the other hand too few bees wont be able to search effectively.
  2. What is their visibility area while flying?
  3. How do they estimate quality and quantity of honey discovered?
  4. How do they remember the path back to their colony once honey is discovered?
  5. How do they communicate quality, quantity and location of honey source discovered to other worker bees in the colony?
I googled to find answers of the above questions and got some amazing facts demonstrating the how amazing these small creatures are.
  1. The worker bees divide the labor depending upon their age. More aged and experienced bees perform foraging. Other worker bees perform other labour work in the beehive like nursing, cleansing, architecting etc.
  2. Honey bees lack stereo vision as we have so they see the world in a different way as we do. They can distinguish high contrast shapes and patterns. They can use ultra violet and polarized light from sun to sense the direction from honey source to beehive. They demonstrate associative learning, color / odour learning and top down processing of information while foraging i.e. they can remember landmarks, colors and odour to come to same food source over many times a day.
  3. Frankly, I faced a hard time to find some reliable sources to find the answer. I have found none. In this case, I will do some guesswork. I believe that bees can remember quantity of food using visual memory, odour and taste.
  4. Bees use a couple of techniques to keep track of distance, sun as compass, Sun Polarized Light (in cloudy conditions), Earth Magnetic Fields and distance measurement techniques involving optical flows. All these techniques are redundant and specific technique is used depending upon environmental conditions. (see here)
  5. To communicate quality, quantity and location of honey source, bees do a ‘waggle dance’ that lets other bees know exactly where they have been, quality and quantity of source. You could put a point in a map about where they have gone based on the information that’s in the dance.
Honey Bees demonstrate one of the efficient form of decentralization and its principles are hard coded in their DNA.

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