think of nothing. Yet Bergdorf looked like the end of the worldwas at hand. There was something here that didn't add up. "Well, get onwith it," I said. "As far as marine biology is concerned I'm as innocentas a Lyranian virgin. Tell me--what's wrong with the oysters?"
"Nothing! That's the trouble. They're nice healthy specimens ofterrestrial _Ostrea lurida_. We found a floating limb with about a dozenspat clinging to it."
"Spat?"
"Immature oysters."
"Oh. Is that bad?"
"Sure it's bad. I suppose I'd better explain," Bergdorf said. "On Earthan oyster wouldn't be anything to worry about, even though it producessomewhere between sixteen and sixty million fertile eggs every year. OnEarth this tremendous fertility is necessary for survival, but here onNiobe where there are no natural enemies to speak of, it's absolutelydeadly!
"Just take these dozen spat we found. Year after next, they'd bebreeding size, and would produce about three hundred million larvae. Ifeverything went right, some three years later those three hundredmillion would produce _nine thousand trillion_ baby oysters! Can youimage how much territory nine thousand trillion oysters would cover?"
I stopped listening right then, and started looking at the map of Niobepinned on the wall. "Good Lord! They'd cover the whole eastern seaboardof Alpha from pole to pole."
Bergdorf said smugly, "Actually, you're a bit over on your guess.Considering the short free swimming stage of the larvae, the sloweastern seaboard currents, poor bottom conditions and overcrowding, Idoubt if they would cover more than a thousand miles of coastline by thefourth year. Most of them would die from environmental pressures.
"But that isn't the real trouble. Niobe's oceans aren't like Earth's.They're shallow. It's a rare spot that's over forty fathoms deep. As aresult, oysters can grow almost anywhere. And that's what'll happen ifthey aren't stopped. Inside of two decades they'll destroy this world!"
"You're being an alarmist," I said.
"Not so much as you might think. I don't suppose that the oysters willinvade dry land and chase the natives from one rain puddle to another,but they'll grow without check, build oyster reefs that'll menacenavigation, change the chemical composition of Niobe's oceans, pollutethe water with organic debris of their rotting bodies, and so change theecological environment of this world that only the hardiest and mostadaptable life forms will be able to survive this!"
"But they'll be self-limiting," I protested.
"Sure. But by the time they limit themselves, they will eliminate abouteverything else."
"If you're right, then, there's only one thing to do. We'll have to letthe natives know what the score is and start taking steps to get rid ofthem."
"Oh, I'm right. I don't think you'll find anyone who'll disagree withme. We kicked this around at the Lab for quite a spell before I came uphere with it."
"Then you've undoubtedly thought of some way to get rid of them."
"Of course. That was one of the first things we did. The answer'sobvious."
"Not to me."
"Sure. Starfish. They'll swamp up the extra oysters in jig time."
"But won't the starfish get too numerous?"
"No. They die off pretty fast without a source of food supply. From whatwe can find out about Niobe's oceans, there is virtually no acceptablefood for starfish other than oysters and some microscopic animal lifethat wouldn't sustain an adult."
"Okay, I believe you. But you still leave me cold. I can't rememberanything about a starfish that would help him break an oyster shell."
Bergdorf grinned. "I see you need a course in marine biology. Here's athumbnail sketch. First, let's take the oyster. He has a big musclecalled an adductor that closes his shell. For a while he can exert aterrific pull, but a steady tension of about nine hundred grams tireshim out after an hour or so. Then the muscle relaxes and the shell gapesopen. Now the starfish can exert about thirteen hundred grams of tensionwith his sucker-like tube feet, and since he has so many of them hedoesn't have to use them all at one time. So, by shifting feet as theyget tired, he can exert this pull indefinitely.
"The starfish climbs up on the oyster shell, attaches a few dozen tubefeet to the outside of each valve and starts to pull. After a while theoyster gets tired, the shell opens up, and the starfish pushes itsstomach out through its mouth opening, wraps the stomach around the softparts of the oyster and digests it right in the shell!"
I shuddered.
"Gruesome, isn't it?" Bergdorf asked happily. "But it's nothing to worryabout. Starfish have been eating oysters on the half shell for millionsof years. In fact I'll bet that a starfish eats more oysters in itslifetime than does the most confirmed oyster-addict."
"It's not the fact that they eat them," I said feebly. "It's the waythey do it. It makes me ill!"
"Why should it? After all a starfish and a human being have a lot incommon. Like them, you have eaten oysters on the half shell, and they'reusually alive when you gulp them down. I can't see where our digestivejuices are any easier on the oyster than those of a starfish."
"Remind me never to eat another raw oyster," I said. "On second thoughtyou won't have to. You've ruined my appetite for them forever."
Bergdorf chuckled.
"Well, now that you've disposed of one of my eating habits," I saidbitterly, "let's get back to the problem. I presume that you'll have tofind where the oysters are before you start in working them over withstarfish."
"You've hit the reason why I'm here. That's the big problem. I want tofind their source."
"Don't you know?"
"I can make a pretty good guess. You see, we picked this limb out of theEquatorial current. As you know, Varnel Island is situated right at thewestern termination of the current. We don't get much littoral stuffunless it comes from the Islands or West Beta. And as far as I canfigure the islands are the best bet. These spat probably came from thePiralones, that island group in the middle of the current about halfwayacross."
I nodded. "It would be a good bet. They're uninhabited. If Harl wantedan isolated spot to conduct oyster planting experiments, I couldn'tthink of a better location. Nobody in his right mind would visit thatplace willingly. The islands support the damnedest assortment of sithsyou ever saw."
"If that's where it is," Bergdorf said, "we can thank heaven for thenatives' suspicious nature. That location may help us save this world!"
I laughed at him. "Don't be so grim, Heinz--or so godlike. We're notgoing to save any worlds."
"Someone has to save them."
"We don't qualify. What we'll do is chase this business down. We'll findout where the oysters come from, get an idea of how bad things are andthen let the Niobians know about it. If anyone is going to save thisplanet it won't be a bunch of Confederation exploration specialists."
Bergdorf sighed. "You're right, of course."
I slapped him on the shoulder. "Cheer up, Heinz." I turned to myappointment calendar and checked it over. There was nothing on it thatcouldn't wait a few days. "Tell you what," I continued. "I need avacation from this place. We'll take my atomic job and go oysterhunting. It ought to be fun."
Bergdorf's grin was like a sunrise on Kardon.
* * * * *
I brought the 'copter down slowly through the overcast, feeling my waycautiously down to the ground that radar told me was somewhere below. Wewere hardly a hundred and fifty meters up before it became visiblethrough the drenching tropic rain. Unless you've seen it you can'timagine what rain is really like until you've been in the Niobiantropics. It literally swamps everything, including visibility.
It was the Piralones all right.
The last time I'd seen them was when I led the rescue party that pulledWilson Chung and his passengers out of the Baril Ocean, but they werestill the same, tiny deserted spots of land surrounded by coral reefs.We were over the biggest one of the group, a rounded hummock barely akilometer in diameter, surrounded by a barrier reef of coral. Betweenthe reef and the island a shallow lagoon lay in s
ullen grayness, itssurface broken into innumerable tiny wavelets by the continual splash ofrain. The land itself was a solid mass of olive-green vegetation thatended abruptly at a narrow beach.
"Well, we're here," I said. "Grim looking place, isn't it?"
"Whoever spoke of the beauties of tropical islands didn't have Niobe
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