Sex
Change
and
Suffocation |
 |
A flashing orange-gold body sent a spark of reflected light into the air near the southern boundary of Orchid Pond. The current increased in velocity here, and made its meandering way through a collection of debris to escape the pond and continue into the rain forest below as a tinkling, fast-moving stream. The immediate area around and including the debris, which had formed a natural dam constricting the flow of water from the pond, was the territory of the wild swordtails. They liked the current, and were more invigorated by its velocity than were either the young guppy or the old fighter. Current was their medium. There were four of them.
Swordtail fish are streamlined in body, the proportions of the three females being somewhat more thick and bulky than those of the lone male. The general shape of them was approximately the same as that of the almost-mature guppy, but they were at least three times his size. They were all bright, orange-gold, the male alone possessing the two-inch sword extending from the base of his tail along the bottom edge, and into the water in back of him.
This black-outlined sword had given the name to his ancestors ages ago; and as the sun shone brightly down, throwing winks and glints of light onto his body, the male was enacting an unusual performance - unusual that is, for most fishes but not for the male swordtail. He was performing a mating display, the ultimate object of which was the healthy female beauty at his side. He would quickly dart in front of her and pause, arching his body much in the same manner as the young guppy in its mating ritual, and quivering in an ecstatic dance of repressed desire. Then, lightning-fast, he would zip in a curving arc to either side of her - back and forth to his original frontal position; but he would zip tail-first, actually swimming backward.
The effect of this movement gave the impression that he was trying to quickly pierce the female with his sword, for indeed, the sharp tip of the sword seemed lethal. The uninterested female took little notice. After his stunning maneuver, the male pricked her lightly with his gonopodium, completing his intricate effort and claiming the prize he desired.
The act of backward-swimming was not extraordinary for the male swordtail, but one interesting fact about him is extremely unusual. He had started life as a female. Born live in the normal manner, a female among seventy-three of her fish sisters and brothers, she had been one of only four surviving females when an infectious disease had killed all the other swordtails in Orchid Pond.
The four were spared due to being immune, somehow, to the disease, and by chance, all four were virginal. Having been of an age too young for breeding when the disease struck their contemporaries, they had never given birth and were left with no prospects for a mate. Oblivious to this fact, they had gathered into their little school of four and had continued busily with their lives.
Into adolescence and beyond, the young female had remained normal, as, indeed, had her sisters. But the lack of an available mate to fertilize the developing eggs in her budding body, had caused a curious transformation in her genetic makeup. Slowly, over a period of six or eight weeks her system had begun to change, and her attitude became one of aggression rather than the usual passivity of a normal female. Her disposition changed also to one of more masculine proportions, and her body chemistry was altered.
A sword, the identifying characteristic of a male, began to develop on her tail, and her anal fin elongated and modified into a gonopodium. Soon, sperm replaced eggs, and when she was nine months old, the transformation was complete. Nature had changed her sex. Now she was a male, and all three of the remaining females were healthily pregnant.
In a short time the pond would have its school of swordtails back, and be replenished with vibrant life impossible but for the curious change of sex of the female which was now a functioning, perfect male in sexual display for his mate.
Off he swam, dispensing with his amorous duties, to spot a water snail on a lava stone a few feet away. Streaking to it in a greedy rush, he tried to snatch the snail's leathery body from its shell before it could retract its muscles and pull itself back into its portable protection. He missed. But his small, strong lips closed around the eyes of the snail, distended on their rubbery antennae, and off they popped into his mouth to become, perhaps, the source of energy for his next brilliant sexual performance. The snail was left with two incomplete and retracted stubs of antennae, and it was totally blind.
Having been just at the opening to a miniature cave in the porous lava rock, the snail, after a cautious wait, had proceeded on its way, consequently entering the hole in front of it, and unknowingly - for it could only feel its way without eyes - beginning a venture it could never complete.
It had just refilled its lung at the surface by ascending the slime trail of another snail, straight up from the bottom through the open water. It had been in the old fighter's calm cove, and when it had finished its exchange of air, a Mourning Dove had plucked it from its floating position and had dropped it unceremoniously into the faster water by the swordtails' territory. Unharmed, it had continued, unperturbed, to be blinded by the fish. Now, as it entered the tiny cavern in the lava rock, it had no way of knowing that the place was a trap for it. Slowly, inexorably, as it continued on its way, the walls of the cave were closing in, becoming the shape of a tube.
The snail proceeded as far as possible to the dead end at the culmination of the tunnel. As it had become smaller and smaller with the snail's progress, the tube was now almost exactly the same dimensions in height and width as the shell of the mollusk, preventing it from turning to either side. The dead end prevented its further advance. It stopped. Questing gently to the right, it tried to turn. Its shell would not turn, being blocked between the narrow walls. Its tiny blind head strained left, seeking advance and purchase for its foot in that direction. The result was the same.
The heavy, muscular foot of the snail, being able to carry it anywhere that suitable purchase could be found, was foiled in its attempt to move the mollusk further. It could not be manipulated into action in a reverse direction. It could not turn the shell enough to pull the creature around and out of the tube into which it had crawled. It could not go forward. It was stuck.
If the snail had possessed eyes, it would have foreseen its error and forestalled its progress in time to save itself from suffocation, for in the tunnel it could not refill its lung. Alas, it was blind. Within an hour, it was dead.
Outside the cave, in the water beside the rock, the male swordtail watched hopefully for the reappearance of his lunch.
(c) 1993 Carson Clippard