Insects: Extending into the Environment
A book excerpt
Andreas Suchantke
From In Context #23 (Spring, 2010)
A remarkable book has recently been published by Adonis Press — an English translation of a German work by the biologist and ecologist, Andreas Suchantke. The book is Metamorphosis: Evolution in Action and presents some of the fruits of Suchantke’s decades of research. Here we extract a small section from a chapter on insects. The text has been abridged and adapted for its appearance here. All the drawings are by Andreas Suchantke. (A list of the book’s chapters follows this excerpt.)
Figure 1. Relationship between skeleton (shown with heavy black lines) and musculature: polarity between vertebrates (below) and arthropods (insects and crustaceans, above) in the musculo-skeletal organization.
The insects (and the other arthropods, crabs and spiders) have an external or exoskeleton, which extends over the whole body, including the legs. The musculature is internal and enclosed in the legs by the tube-like exoskeleton, which requires completely different kinds of joints from those found in animals with a radial endoskeleton (Figure 1). Being encased in an exoskeleton means being sealed off from the environment, coated in a totally dead substance, chitin. After each moulting this chitinous armor is secreted in liquid form through pores in the epidermis and hardens immediately into a wonderfully sturdy, shiny layer. In order to grow, the insect must occasionally free itself from this covering, which, being dead, is incapable of growth.
This shielding tendency is countered by organs that make intimate contact with the environment, such as the sense organs, the extremities, the wings. Depending on which of these two tendencies is dominant, the insect will be more open towards its surroundings or more closed off.
[Let us] take a closer look at the bodily organization typical of insects. The first feature that stands out — not in all, but in very many cases — is the division of the body into the three sections of the head, the thorax and the abdomen (Figure 2). On this subject Goethe remarked:
Figure 2. A female forager bee with a cargo of pollen on her rear legs. The three different body regions can be clearly distinguished, but in the hymenoptera (bees,wasps and ants) these do not quite correspond to head, thorax and abdomen: the first abdominal segment is merged into the thorax (their point of conjunction is discernible as a faint line).
All reasonably developed creatures show three main sections in their external structure. How perfect in this regard, for instance, are the insects! Their body consists of three parts, which perform different life functions and through their reciprocal effects and interconnections raise organic existence to a higher level. The three are the head, the middle and the rear part. If the said parts are very distinct and joined only by means of thread-like tubes, this indicates a state of perfection. This is why the key event in the successive metamorphosis from caterpillar into insect is the successive separation of the functional systems, which in the caterpillar still lay cocooned in a partially inactive and unexpressed condition.
Figure 3. An earwig (Forficula) brings food to its mouth by means of its abdominal pincers. (After Dettner and Peters.)
In its overall organization the “perfect” insect retains much of its original segmentation, even though nothing of these identical segments (often still clearly discernible at the larval stage) is externally visible. This is very much in keeping with the fact that limb primordia [the embryonic buds out of which limbs later develop] form on all body segments during embryonic development. In some insects they persist on most segments into the larval stage (butterflies, sawflies), while in others, such as house fly maggots, they disappear. On mature insects (imagos) [in addition to the normally present legs and wings] limbs can appear in other forms. In dragonflies they take the form of prehensile organs that play a role in mating, in earwigs they become pincers (used, among other things, for pulling their wings out of the pouches into which they are intricately and tightly folded — see Figure 3).
Figure 4. An ant rubs an aphid with its feelers, stimulating it to produce a droplet of sugar from its anus. (From Dumpert.)
More significant, however, is the occurrence of limb primordia on the head, which also consists of several merged segments. Here they are recognizable by the fact that they are arranged in pairs and move by means of joints as feelers and as “chewing limbs” (in insects the upper and lower jaws move horizontally). The feelers are particularly interesting. In many cases they will be found to have kept their original limb-nature. This is especially clear in ants, which use them to exchange tactile vibrations, and even to milk aphids, i.e., by stimulating them to excrete a sugar-rich substance (Figure 4).
Limbs become sense organs, or combine the related functions of perception and movement in one structure. Crickets hear with the tympanic organs located on their long hindlegs; moths, as recent studies have shown, hear with their wings; houseflies taste with the soles of their feet, etc. Completely different from the vertebrates (and many groups of invertebrates) is also the remarkable, highly differentiated structure of the eyes. They do not take the form of spheres set into the head, as in vertebrates and humans (aptly dubbed “gulfs of the external world” by Rudolf Steiner), but consist of bundles of long tubes radiating out into the whole periphery (Figure. 5). The eyes of a large dragonfly, which consist of large numbers of these so-called ommatidia — up to 28,000 in each eye — surround the whole head, enabling all-round vision. This vision is accompanied by constant head movements and at any moment can propel the insect into instant flight when it sights prey, a rival, or a female: perception and movement are one.
Figure 5. “Sensory limbs.” Above left: jointed feelers on a weevil (Balaninus nucum). Above right: an African fly (Diopsis) with its eyes grotesquely perched on the ends of long stalk-like head appendages. Below: polarity of eye structure in the compound eye (schematic) of insects, raying out from the head (left); and the “hollow,” ball-shaped eye, embedded in the head of a marine polychaete worm (right). (After Kaestner.)
Figure 6. Constant angle maintained by a caterpillar crawling towards a light source — and finally being “burnt” by it.
Through the multifaceted subdivision of the field of vision as a result of the integrated rows of individual eyes, the tiniest movements can be registered. Added to this is an ability to magnify time. This is familiar to anyone who has tried to catch flies by hand. To have any hope of success one must approach the fly so slowly that it does not notice the movement, and then pounce suddenly; but even then one is usually much too slow. To describe such a reaction by saying that seeing stimulates movement is to formulate things too dualistically. Here seeing is movement. It can be so compulsive that an insect, once it has set its course for a light source, will hold it unflinchingly and be literally “sucked” into it (Figure 6).
Bees are different in this respect, in that they can fly from a newly found food source straight back to the hive, even though their outward flight took a different route. It would seem that insects do not live “in themselves,” but extended into their surroundings. This means that they are in reality much larger than the tiny physical speck of a creature that our eyes take in. The dragonfly is one with the realm of air and light in which it lives, the bee with its realm of scent and color, the butterfly with the play of light and shade in the world of color it inhabits. This is borne out by the peripheral quality of their sense organs, by their wraparound eyes, and their feelers, which are limbs that have become sense organs. Insects are sensory-limb beings.
Table of Contents of Metamorphosis: Evolution in Action
Introduction
Archetype and Evolution — A Contradiction? Understanding Metamorphosis
An Example of Metamorphosis: Goethe’s Idea of the Vertebral Nature of the Cranial Bones
Formative Tendencies in the Domain of the Leaf
The Blossom
Interim Summary: Metamorphoses — The Key to Understanding the Nature of Life
The Various Forms of Metamorphosis in the Plant Kingdom
Polarity and Threefold Organization: The Dynamics of Metamorphosis
Polarity and Threefold Structure in the Animal Kingdom
The Archetype in Action — Metamorphosis and Threefold Structure in the Evolution of the Animal Kingdom
The All-pervasive Endoskeleton
The Fate of Exoskeleton and Endoskeleton in the Further Course of Evolution
Available from SteinerBooks, http://www.steinerbooks.org. The book is hardcover, large format, 324+11 pages, $50.00.