Last night passed, at least for myself, with little sleep. Slumber was kept at bay by a mind overly occupied, pondering the dilemma we now face of generating steam to drive our engine, but doing so without emitting carbon gasses. We’ve learned from our observation of single-celled pond life and from our recent run-in with the flatworm, that most aquatic microorganisms have the ability to detect the presence of CO2 – the universal product of aerobic respiration. These organisms are adept at locating prey by following a trail of carbon dioxide – an ingenious evolutionary adaption. Our own engine, which burns oil to generate heat, to in-turn boil water for steam, has the same effect on predators. I am amazed that we aren’t now digesting in some micro beastie’s belly!
I am faced with the inescapable conclusion that it is only by luck and fast-thinking that we have avoided such a fate. Surviving these encounters has given us invaluable observational data, and I now feel that we better understand how organisms locate prey, and how carbon dioxide plays a role in photosynthesis and respiration. Therefore it is imperative that we find an alternative source of fuel that when burned, won’t smell to the lions, tigers, and bears of the microcosm like the sound of a dinner bell!
I have just announced my new directive to the crew, and I am pleased to report that they are wasting no time seeking a solution. There is a general consensus that the only way to produce heat without a carbon waste product is to fashion a closed system requiring little more than sunlight.
“Barron,” says Lyra to our engine master, “we are already raising several of those green photosynthetic algae for oxygen. There must be a way to convert the starch bodies they produce into a clean fuel.”
“And starch, like sugar, is made up of carbon molecule chains. You might be onto something there,” rumbles Barron. “Not bad for a biologist,” he adds with a wink.
Deep in thought Lyra ignores the jest. “Carbohydrates,” she says with precision, as if to one of her students back at Cornell. “But how to convert it to a more efficient, high-energy fuel?”
“That’s the question,” I insert. “Sounds like we have promising start. Please have plans and proposals on my desk for review by first bell tomorrow.”
With affirmations from each, Barron and Lyra disappear through the companionway.
I turn to Gyro and instruct him to find us a way free of the aquatic weed forest and the perils therein. “And keep us out of the shadows,” I add. Those flatworms don’t like sunlight, and may be hiding on the underside of these elodea leaves. Best speed, helmsman.”
“Aye sir,” answers Gyro, then relays the message for all hands to take their stations.
The ship rocks gently to port, then to starboard, as Gyro weaves a path through the monstrous plant stems, ever closer to the deeper pond region where the aquatic jungle gives way to the open water. My awareness is keen and my apprehension remains high as long there is danger of encountering another predator of the weedy shallows, but outside, the forest is beginning to thin, and my concerns along with it.
At our current cruising depth, about twenty centimeters, sunlight from the surface is increasing. Green microorganisms streak past the ship. Through the panes of the observation dome I watch the enormous trunks and branches of the aquatic weeds pass astern, every verdant surface abuzz with microbial life. Larger organisms, so distant as to be discernible only as blurry shadows, dart in and out of awareness.
We are almost clear of the forest, almost free from the worry over monsters, when the hand railing slams backwards into my mid section. The panes of the observation dome skew suddenly to starboard as the outside world tilts on its ear. Cyclops comes to an unceremonious stop.
Metal groans. A complaint of our engine vibrates up from below decks. Gripping the rail to keep myself from tumbling across the pilothouse, I scan our surroundings to fathom some inkling as to what has interrupted our escape from the weed forest. It is as the aquatic jungle refuses to let us go.
Before I am able to cast a whispered curse at these perilous weedy shallows, a fleeting shadow of a tendril passes over the watery light above us.
Lyra stumbles from the companionway looking like her trip up from the lower deck laboratory was unusually difficult. “What happened?” she shouts over the protest of iron and wood.
“I haven’t a clue, but it’s like we ran into a wall, or a net,” announces Gyro. “And now we’re stuck.”
“Let’s try to break free,” I tell Gyro. “Ahead, half speed.”
“Answering ahead, half speed,” acknowledges Gyro, then pulls the lever on the engine telegraph.
The deck slips beneath my feet as the ship lurches forward for a breath – then stops.
“It’s like we’re trapped,” declares a frustrated Gyro.
“That’s exactly what it is,” states Lyra from the aft window of the observation dome. “And now I know exactly what has us trapped. Look!”
I turn my gaze to the aft panes. Beyond Cyclops’ tail assembly, a mouth surrounded by six tentacles looms far too close for comfort. Four of those limbs are now wrapped tight around the hull of our ship, and are pulling it closer and closer toward that ring-shaped mouth.
“What is it?” I ask.
“That,” explains Lyra, pointing, “is Hydra, first identified by Carl Linnaeus, father of modern scientific taxonomy, in 1758. And we are in serious trouble.”
As if to emphasize her warning, the hydra’s tentacles tug decisively on the ship. All hands braced themselves as Cyclops lurches half a ship’s length toward the animal’s sphincter-like maw.
“Let’s try again,” I announce, then into the voice pipe I call down to the engine room: “Barron, we are going to try pulling free of the hydra’s grip. We will need as much power as your boiler can muster, mister.”
“All ready down here,” came the engine master’s voice. We are at full steam pressure.”
“Ahead, full!” I announce.
For a moment I can feel momentum pressing me backwards as the sturdy ship drives forward, then a sudden braking as the hydra’s arms reach full extension and responds by pulling us back towards the animal’s mouth, now closer than ever.
“Barron, more power!” – I bark into the voice pipe. But I know that our engine is already laboring as hard as it is able.
Barron’s basso booms back. “The boiler is at critical, skipper. Any more of this and boiler will blow and take the back half of the ship with it.”
I reluctantly turn to Gyro, nod, and watch him ease the engine telegraph level back to half speed. The hydra’s tentacles pull us a full ship’s-length closer to its mouth.
“Jonathan,” offers Lyra, “the hydra is a very simple animal. No muscles, just a network of nerves giving it the ability to retract its tentacles to pull prey into its mouth. Maybe a simple jolt of electricity would confuse its nerve net and make it release us.”
“Get below and help Barron wire the dynamo to the outer hull,” I answer. “Hurry!”
“Skipper,” says Gyro, “if this doesn’t work…”
“If this doesn’t work,” I say, “then we are going to get an amazing view of the inside of a hydra’s gut.” As I speak these words, I have no idea of how prophetic they will turn out to be.
The animal has rotated the Cyclops so that we are now being pulled headfirst toward its mouth. We stare helplessly down the gullet of the hydra, namesake of the many-headed serpent of ancient Greek mythology, a fictional beast that is no more frightening that the real one we currently face. With its next contraction, the monster will pull us into its craw, which even now, is stretching wide to accommodate Cyclops and her crew.
Lyra appears in the pilothouse entranceway, is stunned by the looming nearness of the monster, shakes herself from the momentary shock, then shouts: “It’s ready! Throw the switch!”
“Now, Barron, now!” I boom into the voice pipe. “Contact!”
With the zap of electrical current, the lights of the pilothouse dim. Ozone stings my nostrils. Outside, strings of wavy lightning do a worm-like dance across the hull. The hydra’s tentacles maintain their coiling grip for a count of one, two, three…and just when I start to accept that our plan has failed, the tendrils loosen, jerk back from the ship, leaving Cyclops drifting freely.
“It worked!” celebrates Lyra.
“Full reverse,” I tell Gyro, “and keep us clear of those tentacles!”
Hiding beneath a aquatic plant leaf we observe the hydra, now safely beyond the reach of its tentacles. There is so much we do not know about this monster. We may not have another opportunity like this one for detailed observation. Closer magnification through my telescope reveals some unusual movement on the creature’s skin.
Then we see them – single-celled organisms cover the hydra! These disc-shaped single-celled organisms are ciliates, adapted for living on the hydra’s skin. They use their cilia to create feeding currents for pulling in bits of food, and for walking and hanging onto the hydra.
Lyra postulates that these single-celled partners scavenge bits of food captured by the simple animal. “This helps to keep the hydra free of pesky bacteria. Quite a beneficial arrangement if you think about it. In exchange, the hydra provides its tiny guests a home safe from other predators.”
How, we wonder, does a baby hydra become home to these partners? Which begs the question: where do baby hydras come from?
What luck! We have just seen a nearby hydra capture a red copepod. The crustacean’s battle to escape hydra’s tentacles is short-lived. The unfortunate copepod struggles for a moment, then becomes still.
“Watch carefully,” says Lyra. “Hydra’s tentacles have a stunning effect on the copepod. They are lined with stinging cells! Like other animals in this family, like the jellyfish and sea anemone, those stinging cells inject the captured animal with a paralyzing agent. Luckily the iron hull protected us during our close call.“
We gaze upon the drama with open-mouthed fascination as the utterly immobile copepod is drawn into the hydra’s mouth…alive.
“Jonathan,” shouts Lyra, spinning away from the observation glass. “This is the moment we’ve been waiting for! We have a chance to observe the digestive process from the inside!”
“What are you suggesting,” I inquire with no small degree of apprehension.
Lyra suggests a daring mission, bold even by her usual standards of recklessness, but I listen with interest. “I’ll take the diving bell, and anchor it to the copepod’s carapace, and get a free ride right down into the hydra’s gut!” she explains with unbridled glee.
“Oh, nothing crazy about that idea,” mutters Gyro.
“It’ll be perfectly safe,” Lyra quickly adds after seeing the scowl forming on my face. “The diving bell will stay tethered to Cyclops. If there is any trouble, just pull me out!”
I have to admit: this was an unprecedented opportunity to observe how the hydra digests its copepod dinner. I know that the diving bell is a sturdy vessel, so I grant permission for this bold venture.
It took Barron the better part of an hour to equip the diving bell with the necessary equipment for Lyra to effectively monitor conditions inside the hydra’s gut.
Now we watch with with no small measure of uneasiness as the hydra completes its devouring of the live copepod – and anchored to it, our diving bell with Lyra tucked inside.
Day 13: 1345 hours…
Excerpt from Naturalist’s Log…
What an incredible opportunity! Surrounded by the safety of the diving bell, I am now inside the hydra’s gut! Following the complete engulfment of the copepod into the hydra’s gullet, I have released the anchor hooks so that the diving bell is now drifting freely within the predator’s stomach. Through the portholes I can clearly see cells lining the hydra’s stomach produce a caustic soup of digestive chemicals and enzymes. The crustacean is beginning to dissolve.
My litmus-o-meter is reading a rapid rise in hydrogen ions outside, indicating that acid is building up quickly in the hydra’s stomach. I believe that the stomach lining excretes acid, which digests the meal. As the crustacean’s soft tissue breaks down, its basic molecular nutrients are absorbed into the gut lining, completing the process of digestion.
But there is a problem for the hydra: the copepod’s protective shell is not digestible. How does hydra manage the indigestible exoskeleton?
Further observation into this digestive dilemma is cut short when the diving bell’s chemical alarm rings! The hydra’s stomach acid is beginning to dissolve the bell’s hatch seals (made of frog slime) – and if it does, it will digest me as well!
Day 13: 1430 hours…
“She is signaling!” calls out Gyro.
Just a moment earlier we were observing Lyra’s progress from the Cyclops. The diving bell was clearly visible through the thin dermal layers of the hydra, the copepod dissolving before our very eyes, and then Lyra’s semaphoric flash signaling an emergency of some kind.
I restrain from announcing that “I knew this was going to happen.”
“Pull her out of there – but gently,” I instruct Gyro.
Cyclops inches forward, slowly taking up the slack in the tethering cable. In a moment the cable becomes taut, but fails to pull the diving bell out of the beast’s throat.
“It won’t let her go!” exclaims Gyro. “We have to get her out of there. We need more power!”
“If we pull harder,” I reason aloud, “the cable will snap and Lyra will be digested along with the copepod. No Gyro, I think the hydra itself will come to our aid.”
Gyro gives me a puzzled expression.
“I don’t know why I didn’t see it before,” I muse. “The hydra’s entire digestive system is quite simply a mouth connected to a sack. And, to put it delicately, there are no other openings – it is, so to speak, a sack, instead of a tube. Therefore, it is safe to assume that whatever goes in, and cannot be digested, must come back out…”
“…the same way!” shouts my exuberant steersman.
“Precisely,” I tell him with a friendly clap on the shoulder. “I will make an anatomist of you yet!”
“And here she comes!” heralds Gyro.
Before our eyes, the hydra disgorges the now chemically scoured shell of the digested copepod, and the diving bell with it.
Minutes later, Lyra is safely aboard the Cyclops. She comes to call in my small study where I am rendering the hydra’s capture of the copepod in pen and ink.
“Well, Jonathan,” she says with a sobriety not normally heard in my young naturalist’s usually chipper enthusiasm, “I was storing the observation logs from the diving bell and realized that we have now completed nearly every imperative on our mission check list.”
“And is that not cause for celebration? I believe we still have a couple bottles of that very smooth Kentucky sour mash.”
“I’ll tell the men,” she said, her eyes distant.
“Is everything all right?” I ask softly.
“I wasn’t ready… didn’t expect to feel… I guess I am saying that I’m going to miss this,” she says, forcing a brief smile. I know what she means. The micro world, despite all its perils, has become our world – and the Cyclops our traveling home within it. Leaving behind so much beauty and life is difficult to accept. “I’ll fetch the bourbon,” she adds, leaves me alone in my study, closing the door behind her.
I turn to the porthole above my tiny writing desk. I press my nose to the thick cool glass. The deep infinite of immeasurable liquid blue-green-amber stretches to an impossible horizon… and I feel like leaving it will shred my heart to tatters.