The Great Blue Whale

"...even stripped of these supernatural surmisings, there was enough in the earthly make and incontestable character of the monster to strike the imagination with unwonted power. For, it was not so much his uncommon bulk that so much distinguished him from other sperm whales, but, as was elsewhere thrown out- a peculiar snow-white wrinkled forehead, and a high, pyramidical white hump. These were his prominent features; the tokens whereby, even in the limitless, uncharted seas, he revealed his identity, at a long distance, to those who knew him.
The rest of his body was so streaked, and spotted, and marbled with the same shrouded hue, that, in the end, he had gained his distinctive appellation..."--Herman Melville, Moby Dick

I remember in the biology classes I took in college the way the history of biological scales was laid out to me. The size of the world seemed pretty clear. On the one side lived multicellular creatures like you or I (I presume...and if I'm incorrect, please let me know!), and on the other were the single celled creatures. Single-celled creatures had been hidden from sight for much of human history. Only when van Leeuwenhoek finally brought his lens to their world did we gain the power to see them, for the protozoa were denizens of the microcosmos and could be counted on, for all their multitude of forms, to be microscopic.

Or were they? Anyone who has read my posts here knows I'm obsessed with the way we think of scale in biology. Humans tend to think of ourselves as more or less normal sized creatures from which anything else could be measured as larger or smaller, but this is, after all, not strictly true. To my cat, we are behemoths (who are inexplicably bad at running, hunting, smelling, hearing, or using our claws; but that's a different post), and to the fruit flies I raised, our apartment is an entire world. On the other end of the spectrum, the rotifers we look at are all multicellular creatures, but they are so small themselves that they are sometimes dwarfed by the ciliates they hunt. And then, there is the Stentor coeruleus, a monster in its taxonomical kingdom.


The first time I encountered a stentor, I misidentified it as a rotifer. Laksiyer corrected me and called it the king of the ciliates. That wasn't an S. coeruleus but a smaller variety clinging to a plant; it had the decency to remain in its scale, invisible to my eyes. When I found a specimen of the larger species, it appeared to my naked eye as a dark blue dot hanging on the meniscus of a sample of pond water. When I drew it into my eyedropper, I assumed I was getting an interesting glob of algae or a colony of bacteria. When it moved, I was overjoyed.

Not a white whale, but a blue one, tinted a bright cyan from its partnership with blue-green algae that live in its body. As it moves, it periodically sheds these in bursts of pigmented goop.

What makes the stentor so interesting to me is not merely that they are a very large single-celled creature. It is what the size of the creature allows us in terms of observing and documenting the microcosmos. Under even a low-powered lens, the organelles of the stentor are clearly visible. In particular, its macronuclei, strung along the length of its body like costume jewelry pearls.

Even more interesting, you can see the texture of its cellular membrane. Long striations of fibers up and down its body that allow it to change form and stretch to great lengths. You can see the way its mouth curls into a spiral, a divot where the vortex of its cilia leads its prey.


In this way, the stentor also tickles my other obsession on this site: the aesthetics of scientific viewing. The world presented through a light microscope so often seems to be a two dimensional one, but here is a creature that is aggressively three dimensional. Once again, the light microscope becomes a tool for aesthetic and empathetic sight, in addition to, and as a part of, scientific observation. In looking at it, we get a glimpse of what the world looks like at a microscopic scale. We get a view of what the protists living in its world experience when they encounter this great whale.

Imaginging a Divergent Path

The volvox might be the most exciting bit of algae I’ve ever looked at.  Tumbling through a sample of pond water collected from the surface in the morning, the volvox looks like a creature devised from the mind of a minimalist painter. A simple ball of green dots with some splotches of green dabbed in the center to offset the geometric perfection of the outside. Having tried to paint it, I can say with certainty it is a difficult thing to paint, despite the apparent simplicity of its form.

But the volvox’s visual simplicity belies an organism of extraordinary complexity. For one thing, can a volvox even properly be called an “organism”? Or rather can it be called “an” organism. Like so many of the creatures that live in the microcosmos, the volvox might better be called a complex cooperative of organisms. Not so much a single thing as a colony of differentiated cells working toward a collective goal.

Within these minute stellar spheres live cells for reproduction and cells for feeding and locomotion. In the most rudimentary way, they are a body carting around its reproductive cells from food source to food source. And yes, they move. Quite actively, in fact.

Unlike some creatures from the microcosmos, the volvox makes active use of hundreds of tiny, invisible flagella connected to tiny eyespots to find the light they need to make food to make more volvoxes. In this way, they seem to me to straddle the line between single organism and colony: they are a colony that works together very closely or they are a single organism of incredible simplicity.

The volvox seems like it represents a moment in evolution when creatures moved from being separate and colonial toward being truly multicellular. It represents, also, a moment of divergence, a path not taken on the evolutionary road. As a plant, they move from place to place in search of light. So perhaps there was a moment some time back, when the course of evolution might have moved us toward a world in which the divide between animals and plants was less obvious than we think it is. Where some species of plant would have been motile, roaming from place to place in search of water and evolving cleverer ways of gathering it than through their roots. Just as some species of animals still cling to rocks and live out their lives in a single place, letting tides full of protein and nutrients drift across their mouths.

It is my favorite game in this way to consider the other possible narratives that might have played out in evolutionary history, to wonder where that divergence would have gone and what our world would have looked like with it.