The Sentinel - Arthur C. Clarke [112]
Could the medusa defend itself? Falcon wondered. He did not see how the attacking mantas could be in danger as long as they avoided those huge clumsy tentacles. And perhaps their host was not even aware of them; they could be insignificant parasites, tolerated as are fleas upon a dog.
But now it was obvious that the medusa was in distress. With agonizing slowness, it began to tip over like a capsizing ship. After ten minutes it had tilted forty-five degrees; it was also rapidly losing altitude. It was impossible not to feel a sense of pity for the beleaguered monster, and to Falcon the sight brought bitter memories. In a grotesque way, the fall of the medusa was almost a parody of the dying Queen’s last moments.
Yet he knew that his sympathies were on the wrong side. High intelligence could develop only among predators—not among the drifting browsers of either sea or air. The mantas were far closer to him than was this monstrous bag of gas. And anyway, who could really sympathize with a creature a hundred thousand times larger than a whale?
Then he noticed that the medusa’s tactics seemed to be having some effect. The mantas had been disturbed by its slow roll and were flapping heavily away from its back—like gorging vultures interrupted at mealtime. But they did not move very far, continuing to hover a few yards from the still-capsizing monster.
There was a sudden, blinding flash of light synchronized with a crash of static over the radio. One of the mantas, slowly twisting end over end, was plummeting straight downward. As it fell, a plume of black smoke trailed behind it. The resemblance to an aircraft going down in flames was quite uncanny.
In unison, the remaining mantas dived steeply away from the medusa, gaining speed by losing altitude. They had, within minutes, vanished back into the wall of cloud from which they had emerged. And the medusa, no longer falling, began to roll back toward the horizontal. Soon it was sailing along once more on an even keel, as if nothing had happened.
“Beautiful!” said Dr. Brenner, after a moment of stunned silence. “It’s developed electric defenses, like some of our eels and rays. But that must have been about a million volts! Can you see any organs that might produce the discharge? Anything looking like electrodes?”
“No,” Falcon answered, after switching to the highest power of the telescope. “But here’s something odd. Do you see this pattern? Check back on the earlier images. I’m sure it wasn’t there before.”
A broad, mottled band had appeared along the side of the medusa. It formed a startlingly regular checkerboard, each square of which was itself speckled in a complex subpattern of short horizontal lines. They were spaced at equal distances in a geometrically perfect array of rows and columns.
“You’re right,” said Dr. Brenner, with something very much like awe in his voice. “That’s just appeared. And I’m afraid to tell you what I think it is.”
“Well, I have no reputation to lose—at least as a biologist. Shall I give my guess?”
“Go ahead.”
“That’s a large meter-band radio array. The sort of thing they used back at the beginning of the twentieth century.”
“I was afraid you’d say that. Now we know why it gave such a massive echo.”
“But why has it just appeared?”
“Probably an aftereffect of the discharge.”
“I’ve just had another thought,” said Falcon, rather slowly. “Do you suppose it’s listening to us?”
“On this frequency? I doubt it. Those are meter—no, decameter antennas—judging by their size. Hmm . . . that’s an ideal”
Dr. Brenner fell silent, obviously contemplating some new line of thought. Presently he continued: “I bet they’re tuned to the radio out bursts! That’s something nature never got around to do on Earth . . . We have animals with sonar and even electric senses, but nothing ever developed a radio sense. Why bother where there was so much light?
“But it’s different here. Jupiter is drenched with radio