“It’s fascinating,” Heller said, enthralled. “And you’re saying that life has emerged there despite those conditions. It sounds impossible.”
“I thought so too,” Danchekker told her. “Eesyan had to show me this before I’d believe otherwise. That was what I wanted to show you. Let’s go down and take a closer look at the planet itself.”
They seemed to be rushing toward Surio as vis~~ responded to the verbal cue. The stars vanished away behind them, and .the planet grew rapidly and swelled into a sphere that flattened out beneath them as they descended from the sky. It was in a cool, oceanic phase, and as they plunged downward they shrank in size so that the sea stretching from horizon to horizon looked normal.
Then they were underwater, with strange alien life forms swimming and twisting in the ocean around them.
A black, fishlike creature, vaguely reminiscent of some shark species, seemed to single itself out, their viewpoint moving progressively as they followed it. Then, as VISAR altered the content of the information being injected into their visual systems, the body and soft tissues of the creature became a translucent haze to reveal clearly the structure of its skeleton. The light filtering through the water from above went out suddenly, then came on again, then continued to ificker steadily like a slow-motion stroboscope. The image of the fish remained motionless in front of them. “Day and night cycles,” Danchekker explained in answer to Heller’s questioning look. “ViSAR is speeding them up and freezing this image artificially so that we can observe it. Have you noticed yet that the intensity of the daylight periods is increasing?”
Heller had. She also noticed that the creature’s skeleton was beginning to change subtly. Its spine was shortening and getting thicker, and the bones inside its fins were elongating and differentiating into clearly discernible jointed segments. Also, the fins were slowly migrating toward the creature’s underside. “What’s happening there?” she asked, pointing.
“It’s an adaptation that I thought you might be interested in seeing,” Danchekker replied. “The year is growing warmer, and the oceans around us have begun evaporating rapidly.” VISAR obligingly raised them high above the surface again to confirm the statement. The face of the planet had already changed beyond recognition since their arrival. The oceans had retreated to a series of steep-sided basins, uncovering broad shelves that now connected into vast land masses what had previously been scattered islands and minor continents. Carpets of vegetation were creeping outward behind the receding shorelines and upward into what had been barren mountainous regions. A dense cloud blanket had formed, from which continuous rains were drenching the highlands.
They watched the surface transformation continue for a while, and then descended once more to follow local events in a shallow estuary formed where a river draining water from the rainy areas inland had carved a trench across the exposed continental shelf to one of the diminishing ocean basins. The creature that they had studied previously was now an amphibian living on the mud flats,
with rudimentary legs already functioning and a fully differentiated, mobile head. “It dissolves its bones by means of specially secreted fluids triggered by environmental cues, and grows a new skeleton more suited to an existence in its changed environment,” Danchekker commented. “Quite remarkable.”
To Heller this seemed an overly drastic solution. “Couldn’t it stay a fish and simply move out into the oceans?” she asked.
“Very soon there won’t be any oceans,” Danchekker told her. “Wait and see.”
The oceans shrank into isolated pools surrounded by mud, and then dried up completely. As the climate grew hotter the rivers from the highlands became trickles as they flowed downhill, finally evaporating away before reaching the basins, and what had been the seabeds turned into deserts. The vegetation receded across the shelves until it had been reduced to scattered oases of life clinging doggedly to the highest plateaus and mountain peaks. The creature had migrated upward and was now a fully adapted land dweller with a scaly skin and prehensile forelimbs, not unlike some of the earliest terrestrial reptiles. “Now it’s in its fully transformed state,” Danchekker said. “As Surio goes through a year, the animal cycles are repeated from one extreme of morphology to the other. An amazing example of how tenacious life can be under adverse conditions, wouldn’t you agree?”