The shuttle had lifted off in a gust of pollution a few minutes before, lofted out of a jungle valley in the northern subtropical zone of Arcadia. Security Services Lieutenant Melinda Harrison sighed as she watched it go, but was professionally resigned to her tour of duty.

The mines needed personnel, but using forced labor from the Colonial Correctional Service had been a bad choice. The prisoners' escape had made them the first bandits on a new world, which was not at all good for the burgeoning colonization program. Harrison and this regular draft of guards were here to protect the mines. She glanced at the aqua sky and was glad to heft her gear, march into Reception with the other dozen newcomers, and feel air conditioning wash her perspiring skin.

Papers were inspected, billets assigned, and in an hour the new guards had taken first chow and reported to Orientation. After officers of the Colonial Authority and the mining company addressed them, they were handed over to Chief Medical Officer Varrow.

Some hardness about the eyes told the assignees that Captain Don Varrow had seen it all - more than he had ever wanted. His manner was brusque and silently amused. He swept off his cap and folded his hands behind his back as he stepped up to one side of the display.

"Good afternoon. Welcome to Arcadia." A smile glittered. "I am your CMO. It's my job to keep you alive when the bandits come calling, when you screw up, or when the local life-forms make their presence felt. The last is what I'm going to talk to you about today." He gestured with a remote, and the screen lit with a topographic map of the planet.

In the front row, Harrison was taking notes. She knew her life depended on knowing how to handle the things this planet would throw at her, but she did acknowledge her own xenophobia. They had been told Arcadia had no dangerous megafauna, at least not in these latitudes. . . .

"Arcadia is both terrestrial - hospitable to our biota - and home to some very different products of the biological melting pot. The planetary survey has barely begun, and there are millions of species to be cataloged, but of the less than 5,000 so far described, roughly two percent are inimical to terrestrial life-forms. Indeed, they are predatory on all parts of the Arcadian animalian life systems with the exception of a few rarities that have evolved natural defenses. Today we're looking at just one species. Pay attention - it's lethal, and it's everywhere."

He keyed the screen and a new image appeared. Brows furrowed as the newcomers took in the peculiar appearance, and noted size by the scale bar alongside the specimen.

"Doesn't even look alive, does it?" Varrow said. The object was maybe 25 cm in diameter, brownish-grey in color, an amorphous blob of wet matter. It looked like the droppings of a grass-fed bovine.

"This is Paramorphius fatalis. Grunts call 'em cowpats. As its proper name suggests, it has no particular shape. It's like a sponge in that it has no symmetry, no central organization, is heterotrophic, and exists in an oxidizing environment. But that's where the similarity ends."

Harrison thought back to her basic exobiology primer at Sector Academy. Hundreds of thousands of life-forms had been cataloged on the settled planets, as well as those deemed off-limits, but the infinite variety of life's responses to the necessities of survival never failed to amaze her.

"What we know we've mostly learned in the last year. It's photosensitive, electrosensitive, chemosensitive. It can tell when another organism is within 20 meters of it by particulate analysis and field distortion. When we move, it senses vibrations through the ground, or whatever it's clinging to. It moves by amoeboid locomotion, but so slowly it takes time-lapse imaging to show it. So it waits for prey to come to it. Yes, it's a predator and one of the most lethal on this planet. More than a hundred fatalities during the establishment of the mines were attributed to Paramorphius. Thus the fatalis."

The assignees shared glances filled with distaste but kept silent. Varrow clicked his remote and a cascade of images unfolded. "You're safe so long as you don't touch it, or allow it to touch you. Once physical contact occurs, a rapid cycle of events follows. Down at the microscopic scale, that wet integument is covered with short, razor-sharp filamentary hairs, not cilia but more akin to fungal hyphae. They react like nematocysts. Sensing potential prey brings them online. They are charged and ready, and when contact occurs they erect in less than a thousandth of a second. They penetrate whatever they touch and cling with fine barbs. Once embedded, they cannot let go. Even vigorous pulling elicits only excruciating pain. The barbs release a suite of neurotoxins as soon as they are in place. The toxins go for the motor neurons, they paralyze you in a matter of seconds, and you go down, become as immobile as the predator."

The air in the lecture theater had become grim. No one was taking notes.

"Once the toxins have done their job, pressurized vessels under the integument drive the hyphae about 5 mm into the prey, and they begin to release an incredibly powerful suite of proteolytic enzymes that literally dissolve the living tissue. The mobilized amino acids and complex molecules are used initially for further hyphal growth, sending threads probing through the victim's body, and this occurs in waves as the process continues.

"Shortly after the first wave, nutrients are diverted back through major hyphae to the organism itself, and it begins to feed in earnest. It has a limited storage capacity, but converts the biomass of its prey to tissue almost directly. It is one of the most efficient enzymatic converters we have ever encountered. Paramorphius can double its mass in less than ten hours, and at that point something very interesting happens. It reproduces."

"They divide. No sex is involved; thus the daughter organisms are born feeding. And if the prey mass is sufficient they will divide again in ten more hours. And so on, until the prey is totally consumed.

The truly hideous thing is that a victim of our biomass, contacted in an extremity, will remain alive for maybe twenty-four hours. The predator seals the entry wounds and protects from infection or blood loss. Only organ failure due to progressive tissue destruction brings about termination. In some cases toxins cause anaphylactic shock, and the victim dies in minutes. In others initial pain, before receptors are exhausted, can stop the heart. But in a majority life persists . . . and madness is inevitable."

Varrow switched off the display and smiled as he sat on the edge of a desk. "There are treatments, of course. Blockers for the toxins, and an anti-Paramorphius spray; it's in your issue gear. Hyphae will latch onto boots and clothing. They keep reaching until they find flesh, but you have until that point to use the spray, which will cause the thing to spasm and die. And if you sense contact, you'll have five or ten seconds before the toxins take effect. Sensations range from loss of feeling to blinding agony. Just hit your auto-locator emergency switch, that's the only thing you can do, must do, and will have time to do. We'll be there in minutes, no matter where you are in the region, and at that point the infestation can be stopped chemically and surgically. It scars, but it's survivable."

He pushed away from the table. "Get to know this beastie and watch where you put your feet. Watch what you lean against, and be aware that they hang from branches and drip toxins onto prey below. Yes. When the toxins enter through the pores they take only a few seconds longer to paralyze you. The Paramorphius then releases the branch and falls into contact. They're nothing if not cunning. And, as a parting shot, since they replicate by division, they're virtually immortal."

He laughed, and pocketed his remote. "They look innocent, if repulsive, but they're utterly lethal. Remember that, and leave this planet with a whole skin." He nodded. "Next lecture tomorrow, when we get into the mobile stuff. Dismissed."

As Harrison and her companions left the building their eyes were everywhere, searching for tell-tale swatches of glistening gray. Old hands saw them and laughed, for they knew what they were feeling: everyone on Arcadia got the Paramorphius welcome.

Days later, screaming echoed from the jungle.

Melinda Harrison's head came up with a thrill of xenophobic horror as she laced on her combat boots in the suiting bay. The watch commander had detailed the new guards to patrol with an experienced NCO. She traded glances with him, Sergeant Holloway, a grim-faced man in his thirties who was a six-month Arcadia veteran.

The screams lasted maybe five seconds, chilling, awful. The address system in the bay whistled. "Patrol deploy to locator source in Quandrant C, medical team on its way. Move!"

"Go!" Harrison yelled to her juniors. She heaved on her field pack, pulled on her fatigue cap with its built-in com-jack, voice pickup, and shades, and hefted her weapon. They left at a run, and with an angry bluster of engines a dustoff ship dropped onto the pad. They piled aboard, the back ramp whined up, then the pilot sent them rebounding from the planet's gravity.

The troopers were sweating, mouths dry, glances flicking back and forth as they sat in the troopseats, weapons cleared and butts on the deck between their feet. The pilot flew without concern for their comfort. The brief was to get there as fast as possible, and put the ship down on the coordinates with care. A weaponship was alongside them, and a medical lifter was approaching from the far side of the ugly collection of barracks and laboratories by the mine workings.

Harrison fought G-forces as the horizon dipped and rolled, and when the pilot called out that they were approaching the locator source, her stomach knotted. The image of Paramorphius was stamped into her mind's eye. Every newcomer was thinking the same thing, and it gave her a strange sense of unreality. Her eyes narrowed as the trees came rushing up. The pilot took them over the position in a recon pass, and she made a hand-sign to her sergeant that meant maximum caution dustoff.

"One man down, among trees northeast of the perimeter," the pilot reported. "Company uniform, but there's no report of anyone missing."

"Is this usual?" Harrison yelled to Holloway over the engine whistle.

"Standard medical retrieval, Lieutenant."

"That's what worries me. It's predictable activity."

"Ambush? Wouldn't be the first time," Holloway said frankly.

"Pilot, do we have an LZ?"

"No closer than seventy yards, ma'am," was the reply.

"Take us in. If it's a genuine case, that man's minutes are wasting. We'll secure the location, then call in the medevac. And if it isn't. . ."

"You yell, we shell," was the laconic reply. "Going in."

Their stomachs flip-flopped as the craft dropped in a fast descent. Suddenly the windows were filled with the sulfurous colors of the Arcadian rainforest. It seemed they descended for an age through narrowing confines before landing pads touched amidst a whirl of dust and leaves. Automatic defense guns tracked for body heat or motion, found nothing, and the ramp came down.

Harrison led her team off with Holloway at her side, bowing willingly to the experience of her NCO. Ten yards clear of the machine they dropped into a crouch, weapons presented to every point, and the craft blasted away, shrank amongst the greenery toward the aqua sky.

Alone, Harrison thought. Damn. Well, this is the deep end, Melinda my girl, so swim!

"Trackers?" she barked in a stage whisper.

Meyers was the scantech. The girl scanned the forest undergrowth around them in every direction with a sensor probe for several seconds. "No EMR, forest registers clear, only the locator signal is firm, we have no line-of-sight so there's no bodyscan contact."

Harrison glanced at the sky, heard the engines of all three craft, knew fire support was a word away, and touched her channel select. "Medevac, stand by, we're moving for the contact. If it's clear, rappel straight in." She heard their acknowledgments. "Right, skirmish forward by sections, we are at medium suppression status. Two by two, Jones and Kirsh lead off. Go!"

Meyers gave them the bearing and the first pair advanced ten yards, covered flanking arcs as the next pair moved up, pushed ten further. Then Harrison and Holloway went all the way forward. They were now just thirty yards from contact, but saw nothing through the undergrowth. Great fern-like organisms glistened with condensation amidst the stillness, and light rays made a play as the breeze stirred the treetops far above.

Sweat crawled down Harrison's ribs. She looked down, up, all around, and Holloway nodded, whispered: "Don't ever stop that. Get casual and this planet will eat you alive." He scanned forward with powerful glasses. "Clear."

A signal brought the others forward. Then Harrison and Holloway closed the final distance, stepping cautiously over tree roots, avoiding brushing overhanging vegetation. . . .

On hands and knees, the smell of the forest strong in their noses, they took cover by a massive trunk to look across the sun-dappled expanse of a narrow glade, much too narrow to get a ship into. A body was slumped in the middle of the area. No close cover. Harrison scanned the far side for bodyheat.

"Minutes," Holloway hissed. "He's nearly had it. They need time to stop the infestation."

"Who is he?" Harrison whispered. "What was he doing out here? There's something odd about this." She waved the others forward, spread them along ten yards of treeline, then her eyes met Holloway's.

"I'll go," the Sergeant said grittily. "I've done it more times than I care to remember. I know what I'm looking for." He waited for her permission. "Watch and learn, Lieutenant. It's your first day on-planet."

Harrison leveled her weapon as Holloway readied himself, and at her nod he took off in a crouching run.

He was there in seconds, checked quickly. "Nothing," he hissed on the com channel. "Wait! Yep, it's a cowpat. Half under the guy, right leg. Medevac - " He broke off and Harrison saw him bend to look more closely. "Dammit," he whispered. "I think this cowpat's dead. And that means. . ."

"Ambush!" Harrison barked. "Get the hell outta there!"

Before he could move, the gunship pilot reported movement all around. Meyers had multiple contacts, and a cold fist seemed to jab Melinda Harrison in the guts. First day blues: would she live to see a second?

A warp of tracer fire broke through the clearing from hidden marksmen, and the gunship began to hammer the treeline with its main battery. The supposed victim whirled over, bringing up a pistol. Holloway kicked it desperately aside, lashed out with a hard backfist that spun him over, and then the sergeant was backing for cover, his weapon stabbing muzzle flash in the gloom.

The troopers burned ammunition into the impersonal background of the woodland as shapes moved from cover, and the gunship's firepower slashed down to lay flame among the trunks.

They were trained for this; now they were on ground they understood. Harrison chugged her weapon's slide to lay fragmentation grenades from the underslung launcher as Holloway threw himself into cover. "This is a fallback situation, ma'am." A raised eyebrow underlined his graveyard humor.

Harrison had been about to yell the order when a bandit grenade blew wide of their position. The shockwave bowled her over, her weapon falling away.

She landed on hands and knees, breath almost forced from her, but time seemed to stop, her world was for personal survival only, as she found herself staring into the glistening image of Paramorphius. A live Paramorphius.

Somehow she caught her weight on outspread hands, gloves scuffing dirt, and her face arrested its rush inches short of the lethal creature. Draped over a root that would have broken her nose if she had landed on it, perfectly inconspicuous, it seemed merely a patch of wetness. But in another heartbeat she saw a second Paramorphius beyond. She knew they were sister organisms because the melting skeleton of some ground animal was a chaos of bones and fibers in the shadows.

She felt Holloway take the battledress at the scruff of her neck, and heave her away from them. On hands and knees she flailed for her weapon, panting as ammunition continued to stitch the air.

"We gotta go," Holloway barked, and she did not argue, nodded as she hacked air. "Fall back!" Holloway roared. "Aerial, we need extraction!"

Empty 100-round caseless magazines were dropped free, fresh tanks cracked home, and weapons were charged. "On three, fall back on reciprocal bearing!" Holloway ordered, his matter-of-fact handling offering calm. Bandit riflemen fell silent, changing magazines. "Go!"

They broke cover, clawed through the undergrowth, desperately aware of the need to not touch their surroundings, yet needing to hug the earth for cover. They had made twenty yards when a hideous screaming broke among them, and Harrison's blood ran cold.

She saw Jones, next to her in the skirmish line, rising on his knees and shaking his arm, the blob of a Paramorphius clinging to his right hand, skin contact made between glove and sleeve. Panicking, he fumbled with his other for the ready-use spray in a belt pouch, cracked the top as pain began to hit home, and vented the can' s cloud of silver particles. Suddenly he convulsed, spine bending backward as he collapsed in shaking helplessness. Harrison crawled desperately toward him, yelling into her pickup.

"Aerial, maintain covering fire, we have a cowpat incident! Medevac, we need you!"

"Can you get to the LZ?" was the response as ammunition contained to rain.

"Holloway, procedure?" Harrison snapped.

"Leave the organism here," he replied, right behind her, drawing a machete and putting one foot on Jones' flailing arm. He crouched and swung the razor-honed blade, lopped off the Paramorphius an inch from its contact point, then threw away the blade with a wry expression. "Steel's contaminated with enzymes," he explained. "They'll eat through the sheath and still sear your flesh."

Harrison vented the rest of the can onto the stub of parasite, transferred her weapon to her left hand, and helped Meyers heave up Jones.

Rounds clipped trees over their heads. As they ran far the larger clearing the gunship pilot called with a new problem. "The bandits have flanked you. They picked the ground well! Going in thirty yards to your left, heads down! Now!"

They went down, arms over their heads and weapons under them, feeling the blast wave rush over them. Harrison's stomach flip-flopped as a dislodged Paramorphius fell with a wet squish a few feet from her. This was hell - how could they fight?

"You learn how," Holloway said almost silently at her side, and she realized she was staring into his eyes, her expression telling her thoughts. "You've made a good beginning. Don't blow it."

Jones convulsed violently, tore himself from their grip, and they grabbed him away from the other Paramorphius. "Medevac!" Harrison called. "We need you now!"

"We'll hit the LZ with the troopship," came Varrow's voice.

With a nod to Holloway, they heaved up the helpless soldier and dragged him through a building bluster of downwash as the lifters dropped toward the clearing. Emptying their magazines, the patrol burst into sunlight to find the craft on the ground, ramps down and guns hammering each flank.

Harrison and Meyers ran for the medevac as Holloway herded the others aboard the trooplifter. Harrison swore the ship lifted the moment their boots hit the ramp. Varrow's team was waiting in protective clothing, instruments and drugs in a bearer unit. Jones was grabbed, and was disinfected with a spray.

Gravity slammed them into seats as the pilot sent them climbing from the hot zone, the other ship at their side, the ramp rising as they heard fire ricochet from the belly. They rose out of the forest, and suddenly the pressure was off. The Lieutenant panted raggedly, cleared her weapon, then flicked on her com. "Holloway, report."

"Recovered clean," was the response. "No casualties. Jones?"

"They were in time," she returned as Varrow glanced her way with a confident nod. "Debrief in sixty." She lay her head back, eyes closed, and fought to make her breathing steady.

In a few minutes she opened her eyes to find Varrow holding the removed stub of Paramorphius with a pair of forceps. He grinned. "Welcome to Arcadia, Lieutenant."

Mike Adamson holds a bachelor's degree in marine biology, and is presently pursuing higher-degree studies in archaeology. An Australian resident since 1971, he has a lifetime interest in science and science fiction.

Caleb Brown is an illustrator and biologist living in Montana. By day he drives a delivery van, and by night he draws pictures with his computer.

Tell us what you think.

Endlinks

Life on Mars? - a summary of evidence found by NASA researchers that strongly suggests primitive life may have existed on Mars more than 3.6 billion years ago. The NASA Web site is also an excellent resource for recent news and information on space exploration.

Society of Protozoologists - images, databases, and information on protozoans.

Xenophyophores: Giants of the Protozoan World - a brief summary of the largest protozoan specimen found to date.

Related HMS Beagle article:

Astrobiology: Formulating the Big Picture - an HMS Beagle Opinion on the new discipline at NASA that looks to understand life and its place in the universe.