Lights, camera, action!
The celluloid is rolling! We are now several days into the production of a moving picture documentary. When complete, our film will feature the numerous kinds of microscopic organisms found throughout the pond.
The recent acquisition of several oxygen-producing algal protists has extended how long we can remain submerged, allowing for lengthier observations… and more time to “get the shot,” as they say.
We are currently navigating our way through the dense and occasionally treacherous weedy shallows – treacherous because navigation is more difficult, and one never knows what micro-denizens may lurk in the shadows of this aquatic jungle.
Because of the abundant aquatic plant life and plentiful sunlight, this region offers safe haven for a rich diversity of microorganisms. Again and again we see, whilst filming, the relationship between hunter organisms – and organisms that graze. The hunters, or predators, capture and devour the grazers, in much the way the lion feeds on the wildebeest. The grazers, or prey, do not hunt. Most are green photosynthesizers that make their living harvesting energy from sunlight. And those that do not use photosynthesis as their mainstay glean decomposer bacteria from rotting leaves and decaying micro animals. The compelling study of the relationships between predators, prey, and the environment that supports both is the discipline of Ecology.
Day 13: 0730 hours…
We are deep into the weedy shallows now. Lyra has enthusiastically embraced the photographic survey of our voyage, and these past few days can often be found behind the camera. As the ship steams at meager docking speed, the jungle moves slowly by. All hands are quiet, content to observe the richness of life streaming past the ship, with something akin to awe, or even reverence. The only sound for several minutes is the whir of film moving past the shutter of the prototype British Aeroscope motion picture camera.
“I can’t wait to begin editing,” whispers Lyra, her eye pressed to the eyepiece of our motion picture camera. “This documentary, which I’m thinking of titling ‘Life in a Freshwater Pond: As Seen Through the Eye of the Cyclops’ will change the world, or at least how people see it! It will reveal that the micro world is a living dance of predators and prey, of survival at any cost.”
Gyro cleared his throat, and intoned what I had already been thinking. “Let us hope that we finish it before becoming prey ourselves!”
We are encountering so many new organisms that the camera is rolling constantly! We spy a type of algae made up of cells that connect to each other end-to-end, creating extremely long strands, like hair. The green chloroplast in these cells is spiral shaped, which likely allows it to receive sunlight for photosynthesis no matter where the strand is drifting in relation to the sun.
Nearby we photograph a busy cluster of spherical green colonies. The individual green cells have two flagella each, similar to the species that we now tend aboard ship for oxygen production. These spheres are able to keep their small colony of sixteen cells facing the sun for efficient photosynthesis.
And then a big surprise – a ciliated microorganism that walks! This beasty patrols stems and branches of pond plants, hunting algae. Its legs appear to be specialized cilia that are fused into limbs, and more cilia that create a feeding vortex.
Diatoms surround us! It’s hard to believe that just a few days ago we had to move heaven and earth to get enough oil from these glass-encased algae cells to resume our voyage.
Diatom glass, like all glass, is made of silica. I cannot help but wonder where might the diatoms extract silica for making their glass houses? Equally as fascinating as its glass enclosure is how a diatom buoys itself to hold position at the best depth for photosynthesis; it does so by producing those lighter-than-water oil droplets. And oil, we know, is very high in carbon. From where, we wonder, do they get the carbon – and how might they synthesize oil from it?
Some time back we discovered many uses for diatom products. Aboard the Cyclops we repair windows and portholes with glass harvested from diatoms. We use the oil droplets for fuel and machinery… and as a surfactant when necessary to negate surface tension. In the weedy aquatic jungle there is a thriving variety of the class diatomatae, some green, and some yellow – but I must tell you that the chloroplasts from all varieties of diatoms make a delicious salad!
It is fortunate that we are filming this abundance of Kingdom Protista, because memory alone could never serve as adequate record of our observations. Life, and movement, is everywhere we direct the camera. But how do these free-living single-cell organisms move about? Our film has revealed that all independently living cells fall into one of three groups, generally based on how they get about.
The Amoeboids: Amoebas and their relatives move by extending blob-like appendages that flow like living putty.
The Flagellates: A long whip-like strand, or bundle of strands, wave rapidly, pulling the cell through the water like a propeller.
The Ciliates: These cells are usually covered in a coat of small hairs that move wave-like, in any direction, to move the cell. Ciliatea is the most diverse Class of Kingdom Protista. Some have cilia adapted for walking, others for feeding.
Ciliates are the speedsters of the microscopic world, and most are much faster than the Cyclops at full-steam!
We’ve just now observed a most amazing ciliate that tethers itself by way of a spring-loaded stalk! This is the very same protozoan we observed thriving among the aquatic rootlets beneath Duckweed Base, at the beginning of our historic voyage. I have been eager for the opportunity to study this fascinating genus more closely, and my chance has finally arrived.
When a disruption, such as a predator comes near, the cell instantly retracts the stalk, affectively jerking itself quite suddenly out of harm’s way. After a time the stalk relaxes and extends. With danger no longer present, the cell resumes feeding – a process of drawing in small algae and bacteria that become caught in its whirlpool-like feeding vortex.
“It is the Bell Animalcule,” proclaimed my young naturalist from behind the camera, “but today they are known as Vorticella.” From the safety of the observation deck, she has been filming a colony of these stalked protozoa for several minutes. “They were first observed by the inventor of the light microscope, Antonie van Leeuwenhoek, in 1676,” Lyra proudly recites, “and were later named by…” but before she can grace us with more fact-filled biology history she gasps and focuses her lens on a new development outside – we have been blessed by fortune to catch one of the vorticellids in the act of reproducing!
“You say it’s doing wha…what?” asks a blushing Gyro.
“I can’t believe our luck!” proclaims Lyra. “They reproduce by fission,” she continues to wax while filming. “And just like most protozoa we’ve encountered, prior to cell-division the organism divvies up its internal organelles, then pulls itself into two new individuals!”
“Is that what they do instead of…?” ponders Gyro aloud, stopping himself mid-thought.
“Instead of sex?” asks Lyra, completing the steersman’s inquiring thought. “Actually, yes it is. All protists are genderless. The exchange of genetic material is not required. After fission each new cell is identical in every way – and look, they are about to separate! One of the new vorticellids keeps the spring-loaded stalk. The other one swims away, using its feeding cilia for locomotion. Presumably it finds an anchoring site and grows a new stalk of its own.”
All hands are intently observing the newly anchored daughter cell and the crowded cluster of adjacent vorticella, when without warning every individual retracts lightning-fast on its stalk.
“What happened?” shouts a startled Gyro.
“Something triggered their danger-avoidance response,” answers Lyra, as a shadow passes over the brightly lit vorticella colony.
And suddenly, I am struck with a foreboding sense that our own demise may be at hand.