Monthly Archives: August 2018

Microscopic Monsters – The Age of Discovery, Chapter 16: Pursued by Planaria

 

Day 12: 1515 hours…

Vorticella never lie… will be etched upon my grave – if this day plays out the way the last hour has been going.

We quickly learn what alarmed the stalked ciliates… a planarian! This predatory flatworm has caught our scent – probably sensing the carbon dioxide from Cyclops’ engine boiler exhaust.

“As a wise man once said: you can’t outrun a planarian,” warns Lyra in an analytical tone that defies the peril we were in.

“Watch me!” snaps Gyro, then shouts into the voice pipe: “Barron, give me everything you’ve got!”

We have been trying to evade this denizen of the aquatic weed forest for the better part of an hour, but to no avail. We can neither outrun it, nor out-maneuver it through a maze of water plants and bottom detritus. At every turn the flatworm sways its enormous head from side to side, using its ear-like chemical detectors to track our every move with uncanny precision. I fear that unless we find a way to distract the monster – and soon – we shall become this planarian’s afternoon snack!

“Class Turbellaria, genus Dugesia,” muses Lyra with ironic calm as she peers astern at the looming monster. “Make no mistake, a predator from head to tail. The problem, my dear Gyro, is that the harder you drive our engine, the more carbon dioxide we emit, which is to that flatworm what the smell of frying bacon is to you.”

The helmsman stomps his foot. “But if we shut down the boiler, we come to a stop, and that thing eats us whole!” argues Gyro vehemently.

I am moments from making a fateful decision – the command to abandon ship. I am reasoning that when the planarian captures the Cyclops, we will have a moment or two to escape in diving suits, or alternatively crowd the lot of us into the diving bell, which is hopefully too small to interest the predator. But such an escape comes with harsh consequences, for without Cyclops we will be without protection, oxygen, or food, and our survival in this life-rich micro habitat most uncertain.

“Skipper,” bellows the earnest voice of Barron from the voice pipe. I fully expect him to report that our fuel is gone, that we will soon be dead in the water…our fate sealed as flatworm fodder. But instead the engine master’s thunderous basso announces that he has sighted something nearby: “Off the port side, about two centimeters away, looks like a clutch of aquatic snail eggs!”

Lyra spins to the port frames of the observation dome, training her German-fashioned binocular glasses on the massive green plant stems and branches of the surrounding weed forest. “Barron’s right,” she confirms excitedly. “Jonathan, those snail embryos are probably emitting even more CO2 than we are. Maybe we can use them as a…”

“…a distraction!” I shout, completing Lyra’s thought. “A keen stratagem, but alacrity is of the essence if we hope to effectively trick our pursuer. Gyro, if you can steer us close to those snail eggs – near, but not so near as to get caught in the surrounding gelatinous membrane, then at the closest quarter pull away at full steam…”

“Aye, Skipper!” answers the steersman. “To make this work we will be pushing the ship past the structurally safe limits. Everyone best find something to hold onto.”

I shift my gaze to the aft panes of the observation dome. The monster is nearly upon us. We can delay no longer. I bark into the voice pipe. “All hands, brace for sudden course change!” I turn to my steersman, in whose skills I’ve now placed all of our lives. “Mr. Gyro, please adjust rudder to take us within three millimeters of those snail eggs.”

“Changing course,” acknowledges Gyro as he turns the ship’s wheel gently, moving the Cyclops onto an arc-like path that will bring us to a point three millimeters away from the snail embryo mass in less than ten seconds.

“The planarian is following, just as we hoped,” reports Lyra.

“So far so good,” I tell her, then lean toward Gyro and pitch my voice for his ear only. “Take the propeller out of gear.”

“But, sir…”

“I want to make sure our friend gets a good whiff of those baby snails.”

Gyro moves the engine telegraph lever to neutral. The ship slows. Momentum shoves all hands forward.

“Jonathan, why are we slowing down? It’s almost on us!” shouts Lyra.

The snail embryos, writhing and squirming in their clear egg sacs, loom close off the port bow. I’m not sure how I feel about sacrificing these small molluscs to the planarian so that we can escape, but I know that escaping is preferable to being devoured.

Less than a stone’s throw astern the worm wags its enormous head, seeking the strongest signal that indicates an easy meal. Will it be us, or the baby snails?

“Here we go!” announces Gyro as he shifts the engine telegraph to full forward and throws his entire body into spinning the ship’s wheel to starboard, using all of his strength to hold it into a hairpin turn, fighting the resistance of the rudder. The momentum of the sudden course change pulls on everything aboard the Cyclops, and every micron of her iron hull. I can hear the complaint of metal from all parts of the sturdy ship, and a groan from Gyro whose whitened grip cannot hold the wheel through a turn this tight for very long.

I jump to his side and grasp the wheel, my hands beside his. The resistance from the helm is unbelievable. The wheel threatens to throw the both of us across the pilothouse. The control cables surely cannot take this for much longer. The deck under our feet trembles and a shudder of protest shakes the Cyclops from bow to stern.

“You can do it,” I whisper to the ship.

Suddenly, there is a hand on my shoulder, squeezing reassuringly. It is Lyra. She is smiling.

“We made it!” she shouts above the sound of the grumbling wood, steel, and glass. “The planarian went for the snail babies. We’re safe.”

 

1600 hours…

We withdraw to a safe distance to observe the fascinating yet gruesome epilog of our adventure with the flatworm.

From the planarian’s underside emerges a muscular feeding tube, which methodically begins devouring the baby snails, one after the other, as if they are some irresistible escargot bonbon. The feeding tube has a mouth-like opening that swallows the baby snails shell and all, then takes them into its body where they digest in a tri-branched intestine that runs the length of the beast.

With somber relief I make notes and sketch my observations of this savage feeding process, grateful for our sakes that human ingenuity prevailed again. And as the flatworm feeds, and the baby snails digest within it, I am reminded of the truism that where the choice is to eat or be eaten, nature doesn’t give a tinker’s damn.

Microscopic Monsters – The Age of Discovery, Chapter 15: Lights, Camera, Action!

Day 12: 1015 hours…

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!”

 

1030 hours…

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.

1215 hours…

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!

1330 hours…

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!

1420 hours…

SPROING!

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.