What Does the Viper Fancy? ComputerraOnline Column #6

Have you ever picked wild strawberries? Imagine: you search for berries under the leaves, pick them one by one, and then, once at home, relax and close your eyes... What appears before them? Why?
What appears is obvious: strawberries. It is harder to explain why. The answer “your eyes got used to it” will not do. Only a bright light source can temporarily disable the retinal cells that take the main impact and produce luminous spots before the eyes. The reaction described here is normal and does not disturb the functioning of the eyes.
To nudge you toward the answer, I will describe two other circumstances that seem unrelated to the question.
Predators only very rarely exterminate their prey completely. The point is that predators specialized on a particular prey item (monophages) depend strongly on the abundance of their prey. When very few prey remain, the abundance of monophages falls even more sharply. The preservation of prey is also promoted by the fact that it is impossible to catch every last one of them, and by the fact that their reproduction rate is usually higher than that of predators. A more serious problem is posed by predators with a broad prey spectrum, oligophages and especially polyphages. Their numbers depend only weakly on the abundance of each particular prey species. But fortunately, polyphages eat mainly those prey that are encountered more often, leaving rare prey alone.
Now something quite different. Newborn children come into the world with more or less fully formed eyes, but without the ability to recognize what they are looking at. To “assemble” meaningful images from patches of light and color is difficult. However, newborns are capable of responding to light ovals with two dark spots in the upper part. But to recognize the mother and other people, to perceive the shape of objects and the distance to them, the visual analyzer requires prolonged training. Let me remind you that analyzers include not only the sense organs themselves, but also the signal transmission pathways and the brain centers for processing it. The eyes perceive light; the brain sees!
Everything said above is a consequence of the fact that in order to perceive anything at all, one must already possess an image of what is being sought. This image may be “stitched into” the structure of the analyzer from the outset (as a crude model of a face in the psyche of a newborn), but in the overwhelming majority of cases it arises and becomes specified through experience. As it is used, this image is actualized and refined.
You can see a wild strawberry in a jumble of light and color patches only because you have its image. By comparing the incoming signal with this image, you extract the sought structure from the background. Oh! There it is! You reach out your hand and pick the berry. At once your visual analyzer refines what pattern of incoming information led to successful searching. As a result of this continuous adjustment, after gathering meadow strawberries you will see large berries on long stalks in thick grass, whereas after gathering forest strawberries you will see small berries on low shrubs over fallen pine needles. But, for example, you may simply fail to notice a mushroom or a button lying in the grass.
And where does the picture before our mind’s eye come from? If the incoming signal contains a pattern corresponding to the sought image, it will be extracted, cleared of noise, and presented to consciousness. But if the sought pattern is absent, any noise will be assembled into it, for example the noise that arises in the visual analyzer when the eyes are closed.
This effect is characteristic not only of vision. Do you know that a mother bustling in the kitchen while her child sleeps in the room “hears” that familiar voice all the time? And have you noticed that street noise spontaneously folds itself into the ringtone of your mobile phone, specifically your phone? And if the phone is in your pocket and set to vibrate, then it is no longer the visual or auditory analyzer but the tactile one that gives false activations: it seems to you that the phone has vibrated.
The phenomenon described has many consequences. I will not develop the worldview-related conclusions from the fact that we can perceive only what we are already prepared to perceive, although this line of reasoning can lead to results that are quite unexpected for many of us. For that I would need enough textual space, and you enough time and concentrated attention. Better that I tell a story from my own experience illustrating the switching of predators.
About twenty years ago I kept and bred snakes at home. At my peak I had as many as eight pythons and boas. When in your home, before your very eyes, a female python incubates a clutch that later disperses into a brood of fussy, biting babies, it is an amazing feeling... At that time I often received “write-off” rats after pharmacological studies (animals that had gone through some experiment, survived, but were no longer suitable for subsequent experiments). You load up with several dozen rats, bring them home, and distribute them among the terrariums. The rats in the transport container are hot and frightened; they practically “radiate” characteristic olfactory, acoustic, and visual signals. The snakes catch them literally on the fly. Then a break comes in the experiments, and there are no more free rats. I go to the market and buy rabbits. And before taking a rabbit, the python (which has eaten rabbits many times) will spend several minutes carefully examining the new object. A few rabbits in a row, and soon it will be rats that provoke this hesitation.
When my eldest son was eight months old, he crawled-crawled across the floor, pressed on a terrarium, pushed the glass inward (it had been designed to withstand pressure from the inside), and climbed in to a nearly four-meter python. I ran in from the other room at the noise. The child was standing on all fours in the terrarium and crying, and the python (which had never eaten children before) was cautiously examining from the corner a creature unknown to it. Do you know who suffered most in that story? I did. One cannot really say it was undeserved.
So then, in the psyche of snakes too there are images of what they can search for, and these images too are corrected on the basis of prior experience. One consequence of this is the “careful” attitude of snakes toward rare prey.
When thinking about other animals, it is important to avoid anthropomorphic analogies. We understand poorly what is happening in the head of another person; what then can be said of creatures with fundamentally different psyches! Yet sometimes well-founded assumptions can be made. Here is one example.
On a warm summer night, a viper lies by a mouse trail. It perceives mice not the way we do. Its main sense organs are “ordinary” olfaction and contact chemoreception. The latter is provided by the Jacobson’s organ located in the roof of the mouth, which analyzes molecules collected on the surface of the tongue. Snakes lack a middle ear, and they hear not so much vibrations of air as vibrations of the ground. At night the eyes help only weakly. Perhaps vipers feel the heat emitted by prey. At least other vipers, African bitises, as well as pit vipers related to vipers have specialized organs on the snout for perceiving such heat.
The viper waits for the prey to approach, delivers venom with a precise bite, and immediately lets go so that the mouse does not bite back, scratch, or damage the viper’s precision fangs. The prey will not get far: a few leaps, and its strength will begin to leave it. The tongue and Jacobson’s organ will guide the viper along the path of the prey marked by the bite. By the time the snake draws near, the venom will already have begun digesting the still-warm mouse from within. Time to eat.
So, when the viper waits for its prey, all its sense organs fancy an approaching mouse...