Antics of Ants Mark DuBois
Contrary to reports from Aesop and Solomon, ants are neither industrious nor as wise as once believed. When one tracks daily activities for an individual ant, one discovers that most of their time (greater than two-thirds) is spent resting. For some species, resting time approaches 80% of their adult life. When an individual ant rises from a period of resting, she stretches and acts sluggish for a brief period of time. The frenzied activity one observes near the entrance to the nest represents the activity of many individual ants. Each performs a few tasks, then retires into the nest while another performs a few additional tasks (and so forth). This is not to say ants are unworthy of further study. Personally, I find them fascinating. A few examples are shared below.
Ants belong to the Hymenoptera family Formicidae (all ants and only ants). Almost all ants you observe are females. Males exist briefly; their sole purpose is to mate with virgin queens. Since most queens are sequestered underground, the majority of ants one observes are sterile females (workers). Queens mate only during their nuptial flight and some may live in excess of 20 years. Thus, individual sperm cells remain alive within the queen for that entire time. The gender of an ant is determined by whether the egg is fertilized or not. Fertilized eggs become females; unfertilized eggs become males. Only a small percentage of females receive proper chemical cues and necessary nutrition to become future queens; most are destined to become sterile workers.
At any given moment,, scientists estimate there are 1,000,000,000,000,000,000,000 individual ants alive on earth. Although each ant weighs only a small fraction of an ounce, their combined weight exceeds the combined weight of all humans on earth (all 7 billion plus) [by a significant margin]. It is estimated that 1/3 of the entire animal biomass of Amazonian terre firme rain forest is composed of ants and termites. Each hectare of soil in that region is thought to contain 8 million ants. While ant colonies in Illinois are not nearly as large, many contain 50,000 to 100,000 individuals. Assuming an average length of an ant at 1/32 inch, if one lined all the ants in the world together (head to tip of abdomen), they would form a line which would stretch form the earth to the sun and back roughly 5 million times.
There are over 10,000 described species of ants. This is roughly equivalent to the number of described species of birds. And scientists estimate we may only have formally described 1/2 to 1/3 of all ant species.
Ants have a relatively long fossil history; a few species are known from the Cretaceous (roughly 100 million years ago). Ants have been on earth since before the end of the age of the dinosaurs.
Ants are known from every continent except ANTarctica. They have been found from the tip of Tierra del Fuego to well above the Arctic Circle. The number of species increases with decreasing latitude. Most ants are found in tropical and subtropical climates. For example, one square mile of cocoa plantation at Tafo, Ghana contained 219 species of ants. This is roughly twice the number of species as one finds in the entire state of Illinois or the entire British Isles.
Most ants are predators. In fact, the worst enemy of ants is other ants.Some ants have become highly specialized predators Examples include Proceratium (some species feed exclusively on spider eggs) Stigmatomma which feeds on geophilomorph centipedes, some Dacetine ants such as Smithistruma which feed exclusively on springtails Collembola). All these examples of predatory ants can be found within 30 miles of my home in Illinois.
Many ants orient by chemical means. They use their ANTennae to smell various chemicals. Co-workers often deposit minute droplets of chemicals as they blaze a trail to a food source or new nest site. Other workers then follow these chemical trails. Most ants have a "vocabulary" of between 10 and 20 chemicals. Some signal food sources, others warn of intruders, and so forth. Many of these chemicals are produced in glands located near the ant's defensive weapons (tip of the abdomen and mandibles).
Some ants are capable of swimming. Larger ants (such as carpenter ants) can actually swim across puddles. They use their forelegs for propulsion and their middle and hind legs act as a rudder. Although very small ants become trapped in the surface film, larger ants even orient towards vertical stripes (representing land with vegetation while horizontal stripes would represent open water).
These are just a few of the aspects of ants I find fascinating. If you are interested in literature sources for these facts and observations, please contact me.
Think about some of these items as you walk along the sidewalk or on a trail. And, be careful where you step; there are fascinating animals near your feet.
Credits:
Created with images by quinet - "Ant and aphid" • Hans - "ants wood ants formica" • GLady - "ant ants animal" • Axel Rouvin - "Army ant warriors" • Hans - "forest ant hill huge hill wood ants" • Hans - "ants wood ants formica" • Kurt:S - "ant" • bob in swamp - "Florida Harvester Ant" • quinet - "Ant profile" • akiy2012 - "BeAutifUl Ant" • wildxplorer - "Battle scarred ant" • dullhunk - "A leaf-cutter ant worker carries a leaf fragment back to her colony by Jarrod Scott" • WikiImages - "dinosaur allosaurus skeleton" • WikiImages - "earth blue planet globe" • Dirlei Dionísio - "Ovos de aranha"