The umwelt of a paramecium

On days when it rains and I am stuck inside at a desk, I often find my thoughts return to a single thematic idea: how does a single-celled organism perceive the world? Having recently read Devin Johnston’s Creaturely and Other Essays, I was struck by the author’s same general thought with regard to the higher vertebrates—in this case, the starling: “As science discovers the spectral sensitivities of birds, their sensory world proves alien to ours, their consciousness recessed from us.” Unlike that of humans, the eye of the starling does not filter out the ultraviolet spectrum of light. The organism sees the world with a fourth dimension attached—its world is, in essence, unknowable to us.

Season: organic/plant motifs and structures of microorganisms. Print by Yellena James (

As a sensory experience of one’s environment, this seeing is subjective, what the German biologist Jakob von Uexküll called each organism’s umwelt—what in German literally means “environment,” but which is typically taken as “subjective universe.” The term stands against a typical assumption of modern ecology that all organisms in an ecosystem share the same environment. Instead, von Uexküll argued that the subjective perception of organisms drives ecological interactions—parasitism, mutualism, etc. The entomologist/molecular biologist Alexei A. Sharov, who himself moved from ecology into the emerging field of biosemiotics, contextualizes the theory best with an example from plant ecology:

Uexküll thought that organisms may have different umwelts even if they live in the same place. A stem of a blooming flower is perceived differently by an ant, cicada-larva, cow, and human. Umwelt is not an ecological niche because niches are assumed to be objective units of an ecosystem which can be quantified using external measuring devices. On the contrary, umwelt is subjective and is not accessible for direct measurement for the same reason that we have no direct access to perceptions of other people.

Pistil. Photograph by author.

von Uexküll argued we cannot know the precise, quantified experience of the ant, cicada, or cow, just as Johnston struggles against studies of animal behavior that claim to have understood the way a starling sees. Each organism’s umwelt exists in a reciprocal exchange between phenomenological experience and the biophysical world—one of von Uexküll’s main ideas from the umwelt theory is that each component of this subjective universe has functional meaning to the agent. The stem of a blooming flower may be food, shelter, landmark, etc, depending on the species and context of the interaction. Each organism actively participates in the production of umwelt through these repeated interactions. In Sharov’s words,  the organism “simultaneously observes the world and changes it; the phenomenon which Uexküll called a functional circle.” Because these interactions are tied up with functional use and subjective experience, von Uexküll’s approach to animal behavior could not separate subjective (experience) from objective (biophysical matter), as modern-day approaches to the subject commonly insist—mind makes the world meaningful, a staple of cultural anthropology. In the related field of the philosophy of science, Sharov allies von Uexküll with pragmatism, the school of thought that argues how objects cannot be separated from interpreters.

“Pragmatism is organically related to semiotics,” writes Sharov, and the field of semiotics was born from the Charles Peirce. Semiotics studies the triangle relationship of the components that make up a sign: the sign vehicle, the object, and the interpretant. To clarify the relationship, Sharov gives the example of fire:

A sign is a triadic relationship between a sign vehicle that points to an object by invoking the interpretant (model of an object) in the head of the interpreter […] Smoke is a sign vehicle, fire is an object, and the idea of fire is an interpretant.

The role of the interpreter separates the pragmatists from the positivists, or as Sharov defines them, the realists. Because the universe is a conglomeration of signs—interpretations where distinctions and boundaries are inherently subjective—objects cannot and do not exist independently of how they are perceived and how meaning is imposed. It was in meaning, then, that von Uexküll placed function and usefulness. Function was equated with biological adaptation, that which helps an organism best-survive in their environment, maximize their fitness, and pass on their genes—the function circle of which von Uexküll spoke was thus the cycle of interpretation of sign and subsequent action on the world. Sharov quotes the German biologist’s example of the human eye:

Even the simple blink-reflex, caused by the eye being approached by a foreign body, does not consist of a mere sequence of physical causes and effects, but of a simplified functional circle, beginning with perception and ending with effect.

Before the blink. Photograph by author.

The clutch of the umwelt argument is that biological adaptation = sign communication. This discussion is given an ethnographic flair by anthropologist Eduardo Kohn in his study of transspecies engagement in the village of Ávila, Ecuador, home to a Quichua-speaking Runa community of the Amazon basin. Kohn draws upon the how the community comes to make sense of and interpret their dogs’ dreams to illustrate the larger theoretical and methodological dilemma of how to approach this kind of clash of umwelten. In seeking to make sense of an ecology/ethnography of Ávila where humans are not the only selves, where the community’s dogs are not organisms-as-objects, Kohn too, like Sharov, refers to von Uexküll and Peirce. The anthropologist’s goal is to move anthropological discussions of human–animal relationships beyond a polarization between nature and culture, between subject and object, and semiotics offers one pathway to do so.

Kohn notes how Peirce’s system recognizes how symbolic reference can be constructed out of basic non-symbolic sign processes. Much of anthropological discussion is tied up in issues of symbolic meaning—take the still-read classic ethnography of symbolic anthropology and Victor Turner, Forest of Symbols: Aspects of Ndembu Ritual (1967). Kohn notes how symbolic reference is a distinctly human form of representation, but is one that is not mutually exclusive from, and is in fact embedded within, those modes of representation that are found throughout the biological world. He argues that these more basic forms of representation—interpretation and adaptation to the environment—are intrinsic to even the simplest forms of life. “Even the simplest organisms,” Kohn writes, “are inherently semiotic.”

Kohn demonstrates his point with the cilia of paramecia, a group of single-celled ciliated protozoa. The cilia, which cover the body of the organism, allow the cell to move synchronously, 2,700 μm (roughly 12 body lengths) per second. To Kohn, these cilia function as an adaptation, one that facilitates the paramecium’s movement through its aquatic environment. The specific qualities of the cilia—organization, size, shape, mobility, etc.—both capture and reflect specific features of water, namely the resistance of the medium that the protozoan must swim against. Kohn sees this process as his semiotic act:

This adaptation is an embodied sign vehicle to the extent that it is interpreted by the subsequent generation with respect to what this sign vehicle is about—the relevant characteristics of the environment. This interpretation, in turn, becomes manifest in the development of a subsequent organism’s body in a way that incorporates this adaptation. This body (with its adaptation) functions as a new sign representing these features of the environment, insofar as it, in turn, will be interpreted as such by a subsequent generation in the eventual construction of that generation’s body.

“Life, then,” writes the anthropologist, “is a sign process.” And the sign process is adaptation to an environment, that reciprocal relationship of perceiving and subsequently acting on the environment over spatial and temporal scales that von Uexküll defined as central to his concept of the umwelt. “A somebody—or a self,” as Kohn calls it, “is not necessarily human. And it need not involve symbolic reference or the awareness often associated with representation for it to qualify as a self.” Adaptation, then, is biological agency, is a subjective acting upon, and the life of a cell is a “sign process, albeit one that is often highly embodied [in biology] and non-symbolic.”

Let’s return to the paramecium and the starling. Johnston writes that to begin to see how the starling sees, we would have to hold a black light up to the world—only then could we physically see the spectrum of light invisible to our trichromatic vision. But this seeing would only be physical—the umwelt of the bird would still be a mystery. We would have to inhabit the phenomenological life of a starling, explore those ecological relationships, those subjective sign processes, that constitute how the starling sees the worm, sees a conspecific’s tail feathers. And what of the paramecium?

"Paramecium Caudatum Ciliate Protozoa in Conjugation." Print by John D. Cunningham.

How would the protist perceive its freshwater environment? Its cilia? The bacteria, algae, and yeasts it calls food? A team of biologists led by Harvard L. Armus concluded, by using voltage as a reinforcement, that P. caudatum (above) may learn to discriminate between different brightness levels. So the organism can learn, discriminate. But, as with the starlings, can we know their psychology, their umwelt?

Perhaps Johnston is right and the umwelt, of a starling or a paramecium, is simply unknowable from a human standpoint. In his “A stroll through the worlds of animals and men,” von Uexküll gives his hand at writing out the various possibilities of subjective experience had by subjects such as a tick, a fly, or a snail. He attempts to imagine what life would be like for organisms with different sensory and motor abilities than our own. On the paramecium, he writes:

Of all the different things in its environment, its Umwelt takes in only the ever-identical receptor cue, which, whenever, wherever, and however the Paramecium is stimulated, impels it to the motion of escape.

The description, however well-intentioned, does fall short in describing the experience of being a protozoan. It is not for lack of trying, but rather the (im)possibility of the task. With a conclusion much the same as Johnston’s reflection on birds, Thomas Nagel argued the inability of one species to fully understand the mental/subjective state of another. Nagel’s conclusion returns to semiosis, the particularity of how an interpreter makes sense of the three components of the sign—as Peirce and later Sharov noted, each distinction made within this process is a subjective one. And because every subjective state is knowable only to the subject experiencing, knowing what it is like to be a starling, or a bat, or a paramecium, is an impossibility.

But even if the desired end is impossible, does that mean such a task should not be attempted anyway? Our world consists of ideals, which to many will never be obtained—the notion of World Peace is but one. Yet this has not stopped actions to uphold human rights, to end wars, to reduce human suffering and conflict. Impossibility, “we shall never X, Y, Z,” lies along a gradient. We anthropomorphize, insert our own subjective experience into the world of non-humans, simply because it is what we know, because this is our system of signs, symbolic meanings—why Robert Hooke could not help but compare the previously unknown details of the microscopic world to those of the wider human world of which he was a part. Perhaps it is simply that the logic-driven mind of scientific inquiry is inadequate to reach closer toward the possibility spectrum of the gradient.

Art has always been one way to mediate tensions like these. Whether through experimental-minded writings like von Uexküll’s on paramecia or watercolor paintings, the artistic hopes to bridge various umwelten more so than an alpha of 0.05. The paintings of Emilie Clark might be one answer to Nagel. Clark, a painter based on Brooklyn, NY, has worked on a series of projects involved in life on a microscopic scale. In a 2004 gallery showing, Pondering the Marvelous, Clark responds to the writings of Mary Ward, a 19th-century Irish natural historian and painter, specifically Ward’s A World of Wonders Revealed by the Microscope. In imagining Ward’s writings as personal letters to the artist, Clark produced two series of her own watercolors—the first based on Ward’s description of Ireland’s microscopic landscape, and the second on Clark’s own collection.

Untitled MW-#50. Painting by and courtesy of Emilie Clark.

Untitled MW-#12. Painting by and courtesy of Emilie Clark.

The paintings are not meant to be illustrations of the organisms’ umwelten, and nor do they achieve this ideal. But in contrast to von Uexküll’s thin prose or Armus et al.‘s conclusion, these paintings play with the possibility of “what if?” And it is this play that creates an opening in our imagining of the umwelt of other species. Perhaps best said by the poet–immunologist Miroslav Holub, the act of play allows us, simply, to “avoid the aridities of rationalism.” This is exactly what Johnston implies when he ponders whether, on the topic of the starling’s sight, “we will find a rhyme, rune, or ritual to reveal the vibrant hues of ultraviolet light.”


One response to “The umwelt of a paramecium

  1. Pingback: The umwelt of a paramecium | The Integral Landscape Café |

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