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Thursday, January 22, 2015

ANTS


Proverbs 30:25
Ants aren't a strong species, yet they prepare their food in the summer.

The word myrmecology was coined by William Morton Wheeler (1865–1937), although human interest in the life of ants goes back further, with numerous ancient folk references. The earliest scientific thinking based on observation of ant life was that of Auguste Forel (1848–1931), a Swiss psychologist who initially was interested in ideas of instinct, learning, and society. In 1874 he wrote a book on the ants of Switzerland, Les fourmis de la Suisse, and he named his home La Fourmilière (the ant colony). Forel's early studies included attempts to mix species of ants in a colony. He noted polydomy and monodomy in ants and compared them with the structure of nations.

Wheeler looked at ants in a new light, in terms of their social organization, and in 1910 he delivered a lecture at Woods Hole on the “The Ant-Colony as an Organism,” which pioneered the idea of superorganisms. Wheeler considered trophallaxis or the sharing of food within the colony as the core of ant society. This was studied using a dye in the food and observing how it spread in the colony.

Some, such as Horace Donisthorpe, worked on the systematics of ants. This tradition continued in many parts of the world until advances in other aspects of biology were made. The advent of genetics, ideas in ethology and its evolution led to new thought. This line of enquiry was pioneered by E. O. Wilson, who founded the field termed as sociobiology.

Certain Ants are Used as Living Food Storage Vessels

Today I found out some ants are used as living food storage vessels by their colony.

While honey bees will collect and store their food in combs, certain species of ants take a different route, using the bodies of some of their fellow ants, often the larger bodied ants of the colony called “majors”, to store what they need. Worker ants bring the “honey” or “honeypot” ants things like nectar, water, body fluids and fats (from prey such as caterpillars and termites) to store in case of drought or other times where resources are scarce. Depending on the size of the colony, there may even be thousands of these honeypot ants in a single nest, doing nothing but sitting there and waiting for their stored sustenance to be needed.

As the other worker ants bring the liquid foods to the honeypot ants, their gasters (rear portion of the ant) will swell larger and larger until they become so big they can’t move around. This isn’t that big of a deal for them as they also tend to become so big that they wouldn’t be able to leave the nest anyways as the paths out are too small. These honeypot worker ants can even swell to as large as a small grape.

In order to retrieve food from the honeypot ants, other worker ants will stroke the antennae of the living storage vessels. When this happens, the honeypot ant will regurgitate a little of the sweet liquid it has stored in its abdomen for the worker to eat or distribute elsewhere, such as feeding the queen.

Given the fact that honeypot ants contain such a rich source of tasty liquids inside themselves, they tend to be sought out by predators, even humans. As such, they usually are “stored” deep within the nest to protect them. Nevertheless, Honey Badgers and other such predators will seek out these swollen ants and eat them when they find them. Some Native American tribes, as well as Aborigines, were also known to regularly harvest honeypot ants, biting off the swollen abdomen for a sweet treat.

Most species of ants actually have the ability to do something similar to honeypot ants. Specifically, they have two stomachs, one for their own use, and one for storing food for the colony’s use. This second stomach is capable of swelling a bit to hold liquids for transport back to the nest. Once back, they can then regurgitate this liquid for other ants in the nest to consume. With honeypot ants, their storage organ is simply capable of expanding to a much larger volume than what is possible in most other types of ants.

Many species of ants communicate with their nest-mates using chemical scents known as pheromones. Pheromones can be used in many ways by ants and other animals (including humans), but we are most interested in how ants use pheromones to direct each other through their environment---this particular task is closely related to the problem of directing the flow of information through a network.

Consider a colony of ants that is searching for food. Casual observation of an ant colony will reveal that ants often walk in a straight line between their anthill and the food source. The concept of an "army" of ants marching in file has permeated popular culture, and most people who live in ant-friendly locations (nearly every human-friendly place in the world) have seen this particular behavior first-hand. Marching in a straight line, which is usually the shortest route, seems like an obvious solution to the problem of efficient food transportation, and we might pass it off as uninteresting.

Of course, we humans would do the same thing, and in fact we do march in lines along direct routes when we travel in groups as caravans. When we look down at a line of ants from above, we might simply think "so what?" But we have huge brains compared to ants, along with extraordinarily complicated visual systems (over 25% of the human brain is devoted to vision), and we also have a more elevated view of the terrain. Even with these advantages, efficient route-finding, especially through an environment that is full of obstacles, is not an easy task for us. Given ants' comparatively simpler brains, we cannot pass their collectively intelligent route-finding off as trivial. So how do they do it?

Suppose that an ant colony starts out with no information about the location food in the environment. The human strategy in this case would be to send out a "search party" to comb the surrounding area---the scouts who find food can bring some back to the home-base and inform the others about where the food is. Ants do search for food by walking randomly, which is similar to the human "combing" approach, but two issues prevent ants from implementing a human-style search party directly. First, how can an ant-scout, upon discovering food, find its way back to the nest? Second, even if a scout makes it back to the nest, how can it inform the other ants about the food's location? The answers lie in a clever use of pheromones.

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