A 1600 Work I
1600 Work II
1600 Work III
Bill Long 5/7/07
Go to the Ant, You Sluggard...
Now is an exciting time for the study of Arthropods. Comprising more than about 50% of the described animal species (more than 1,134,000 species of Arthropods), these "foot-jointed" creatures include everything from the Arachnida (spiders) to Trilobita to horseshoe crabs (Merostomata) to centipedes (Chilopoda) to millipedes (Diplopoda) to the Insecta. In fact, there are 18 Classes of these creatures, with many of them exhibiting stunning expressions of ingenuity, coloration, adaptation and engineering that would leave some of our most highly-trained engineers breathless. Nearly 1,000,000 species of arthropods are from the Class Insecta. One of the few dozen Orders of Insecta is the Hymenoptera, comprising the sawflies, wasps, bees and ants. They are so named because they have a "hymen" or membrane and "pteron" or wing. All 12,000 or so species of ants (current number; only about 8,800 of them when Wilson wrote his magnificent treatise on The Ants in 1990) belong to the family Formicidae. Because there are so many species in one family, taxonomies have "evolved" to include not just things like "superorders" or "infraorders," but also about 18 "subfamilies" of ants--with names ending in "inae" (i.e., Formicinae, Myrmicinae).
These small creatures, which may comprise nearly 20% of the total terrestrial animal biomass, have been a favorite in scientific study since the early 19th century. The landmark recent work on them was Holldobler and Wilson's Pulitzer Prize-Winning The Ants (1990). Because of the overwhelming nature and scope of the information presented, e.g., more than 50 pages at the beginning simply describing various genera of the ant subfamilies, the book is more a "reference" book for scholars than a quick read for those who have always been interested in ants. Bits and pieces of it appear throughout the Internet, as scholars have used its basic information to refine their own material. The incredible complexity of the ant itself (Wilson's diagrams of various parts of the ant includes more than 50 named parts--p. 5) must be overlaid on all the terminology that defines each genera. Thus, I can easily see how a fascination with ants can be the work of a lifetime, and that one can only be expert in describing some of the bewildering diversity of these creatures.
I once recall a conversation with a fellow student while I was an undergraduate at Brown. He had Prof. Abe Sachs, an Assyriologist, as a professor. Sachs, who was 60 at the time, used to tell his students that the tablets in his office and museum, numbering a few hundred, were more than enough to keep him busy for the rest of his life. At that time (age 19) I felt immediately sorry for Prof. Sachs. 'How,' I thought, 'could one be satisfied with studying a few tablets when the entire universe is before us?' But what I didn't know as a young man, when I thought all knowledge was easily accessible to me, was that almost any very technical area of study can open up tremendously wide vistas when it is examined with care, patience and depth. Thus, a study on the ants not only gives us priceless and thought-provoking information on all kinds of odd behaviors in the natural world, but it opens up the universe in a nutshell.
How I "Got Into" Ants--and Slave-making
I suppose I would have just written these two or three "Arthropod" essays on other topics had I not run across the word "dulosis" in one of the Kids' Spelling Bees. As usual, words open up worlds for me, and I learned that "dulosis" is actually a very common word in the study of ants, and means "the practice, exhibited by certain genera of ants, of enslaving other ants or colonies of ants." I then became fascinated with the process of "slave-making" in the ant world.
When you begin to study almost anything in nature, you immediately have to enhance your vocabulary. So I did here. I learned that there were two kinds of "slave-making" ants, those called "obligatory" and "facultative" ants. The former must make slaves in order to be able to function themselves, while the latter may create slaves, yet don't need so in order to survive. I learned also that dulosis (from the Greek word doulos, meaning "slave") is part of a multi-pronged phenomenon of temporary parasitism, permanent parasitism (called inquilinism) and various kinds of slavery. The latter is often accomplished by murder or deception that, as one commentator says, would leave many modern spy services impressed.
Take, for example, the ant with the eerie name Bothriomyrmex decapitans. (bothrion is the Greek word for "small trench" and is used to describe an indentation on the ant's head). As Holldobler and Wilson describe it, assassination is the technique used by this and another species, B. regicidus. These temporary parasites live in North African deserts. The B queen seeks a nest of the host ant, in this case an ant from the genus Tapinoma. Now we follow their description:
"She allows herself to be accosted by the aroused Tapinoma workers and dragged by them to the interior of their nest. There she takes refuge among the brood or on the back of the Tapinoma queen. In time she settles down for good on the back of the host queen and begins the one act for which she is uniquely specialized: slowly cutting off the head of her victim" (p. 451).
When this is done, the B queen takes over as the sole reproductive ant in the T colony, and the colony eventually becomes dominated by her offspring and herself.
Like that example? Well, there is another. The European species of Formica exsecta seek to colonize other species of the Formica genus, the fusca group. The exsecta queen is smaller than other predatory species, like the F rufa, and thus tends to be treated with less hostility by the host workers. Here is how she infiltrates her target:
"Queens approached by the host workers lie down and 'play dead' by pulling their appendages into the body in the pupal posture. In this position they are picked up by the host workers and carried down into the nests without any outward show of hostility. Later they somehow manage to eliminate the host queen and take over the reproductive role" (p. 451).
This dulotic character of many ants continues to stimulate research. For example, Professor Joan Herbers of Ohio State Univ. has devoted much study to the North American slavemaking ant Protomognathus americanus, which apparently enslaves three host species of Temnothorax ants. Just to show you that even if you knew all the players without a scorecard, you might still be in trouble, Herbers tells us that the Temnothorax were formerly Leptothorax ants. I thought that they had changed the name on me recently... She is interested in studying the frequency of raiding, destructiveness of slave raids and the types of aggression in these situations. How various slavemakers interact with diverse hosts can then become a near full-time job.
When King Solomon urged his hearers to "go to the ant, thou sluggard; Consider her ways, and be wise" (Prov. 6:6), he couldn't have foreseen that modern scholars would eagerly take his advice. Maybe that ancient wise man was truly wise in this way, too--that by studying the ants, we not only learn about the nature of industriousness, but that we might learn something about predation, deception, inquilinism, warfare and colonization that can tell us not only about ants but arguably about the most interesting species in nature--Homo sapiens.