Invisible phantoms, dire and deadly, the ethereal shadows of the world's deepest oceans and closest seaside bays. Survivors of 650 million years, the heirs of a dynasty exceedingly more ancient than that of the first sharks or earliest dinosaurs. The scourge of beaches world-wide and heartless killers of more human prey than the fearsome sharks themselves. Pests that ride every ocean current, the bane of surfers at sizes varying from that of the most infinitesimal marble to a colossal 200 feet. Even when dead they can kill or wound the ignorant. On sea and seashore, they are everywhere, there is nowhere to hide. No one sings the praises of the dreaded jellyfish.
Yet wait, and look closer. Give the jellyfish just one more chance. Peer into the world of the ocean, deep and shallow. It is fluid and without structure, cold and night-dark, alternating with patches of vivid life and barren wastes, shifting boundaries and strong ocean currents, filled with predators, prey, and human oil spills. A gathering of creatures now glides by with peerless grace, each resplendent being possessing psychedelic elegance. Each creature is an individual celestial majesty, great luminous orbs with willowy tentacles, some housing a rainbow of up to two hundred small, vivid fish. Hardly the beached mound of jelly commonly seen in so many coastal areas, here the supreme ocean being drifts free, each simple characteristic acting in flawless harmony to create a creature that is perhaps the world's most successful life form. Though vulnerable, frail, and quick to perish on land, the jellyfish thrives in the cradling water-world of the oceans where no bones are needed for structure. In water, the bubble-light drifter may sail the currents to wander the oceans or, with pulses of its bell, utilize its inborn jet propulsion for faster travel. Some, such as a species of moon jellyfish, only 1.5 inches in diameter, pulse up to 3600 amazing feet a day: the equivalent of a six-foot human swimming 33 miles.
With the mere essentials of a nerve net, but with no brain to guide it, with a gut, but no anus, with only two layers of skin, eyeless and brainless with sparse sensors to sense danger, food, direction and light, with but a single muscle and no bones, the jellyfish is a simple creature. Radiating ivory lines around the bell (known as radial canals) carry nutrients throughout the jellyfish, as the feathery oral arms that drift beneath the jellyfish help it to consume food and to carry the eggs of the female. The jellyfish's dreaded toxic tentacles are useful as much for the capture of food as for defense. Jellyfish have no control over exactly what it stings, for whenever its cnidocyte-cluster cloaked tentacles brush up against something, the nematocysts (stinging cells) shoot forth into the offending subject and inject the jellyfish's paralyzing poison. Though the Australian box jellyfish and sea wasp both have venom more potent than a cobra, and both could easily kill a human, many jellyfish are harmless. The majority, in fact, produce a sting which is less potent than that of a bee. Traveling the currents of the ocean, the jellyfish moves with rhythmic pulses, stretching out its tentacles in hopes of nabbing a meal to feed its voracious appetite. That meal will consist mainly of the bountiful larval fishes, jelly combs, young blue crabs, shrimp, and even the other jellyfish it comes across (sorry, no humans). Some, such as the upside-down jellyfish, harvest food from the photosynthesizing algae they grow on their bodies and never need to utilize their powerful tentacles.
The world is a dark, foreboding place when one of the 200 species of Schyphozoa, the true jellyfish, enters it as one of the 40,000 eggs an adult jellyfish sheds a day. The ocean is home to many predators which enjoy dining on the delicate jellyfish at all stages of its life, such as fellow jellyfish, sea turtles, seagulls, ocean sunfish, starfish, snails, blue rock fish and humans (many of whom consider the jellyfish a delicacy when served fried or steamed). When it hatches, a small ciliated larva, known as a planula, is born. Wildly beating its cilia, the planula concentrates all its efforts in attempt to latch onto something solid. Later, if the spring season was warm, preventing dangerous freshwater runoff, and if it has not already been eaten by predators, the jellyfish assumes the distinctly non-jellyfish-like form of the polyp, resembling a miniature crystalline plant. So un-jellyfish-like are the polyp forms, that many polyps have yet to be linked to their medusa forms. As a polyp, the jellyfish may live many years budding clones of itself, until it begins to split into many flat, saucer-like segments, progressing to the stage of a strobila, a stage which may consume many years of the jellyfish's life, in turn. Each segment of the strobila gradually separates and drifts off in the form of the ephyra, a flat, young jellyfish. As it ages, the ephyra matures into the magnificent form of the medusa: the adult jellyfish so named for its resemblance to the Greek goddess Medusa. The medusa may range in size from that of a bell of eight feet and tentacles that reach 200 feet (Arctic lion's mane jellyfish), to a total size of that of a marble (some moon jellyfish), depending on the type. In the medusa stage, the jellyfish may only live one single season before it freezes to death in the harsh waters of winter.
Now the year is 3000. Humans have accomplished what they consider to be a great achievement, albeit by accident. Pollution has killed off the last of the jellyfish. At first there was little difference, aside from less stings at the beaches. Fifty years pass. Now imagine a world without otters, crabs and sea turtles. Imagine a world devoid of fish, oysters, or starfish. A dismal world lacking sharks, dolphins, birds of the shore and whales. The ocean is now a vacuous abyss, home to nothing but water and a species of algae considered inedible by fish. The people cried when they saw what had happened, but it was far too late. Without the jellyfish to eat the sea combs, the oysters were gradually destroyed by the onslaught of the sea combs that consumed their young. Small fishes of the sea, in the absence of the sole protection the jellyfish offered in a savage world where the jellyfish may be the only other solid object, did not receive the protection, nor the food offered by the jellyfish, and were forced to find algae and nutrients on their own to eat. After seriously depleting the algae, they too were consumed in great numbers by the larger fish, who prospered by such a feast. The marine mammals and other sea predators such as sharks and sea hawks prospered with the sudden increase in large fish. Soon all the small fish were gone, and the large fish began to die. Before the humans could stop it, the marine mammals and large predators had become extinct. The year is now 3100. From lack of sea creatures, the mammals that fed on the sea creatures became extinct as well, thereby slowly killing off, by the dreadful fate of starvation, many of the other land mammals. Insects and plants are overrunning the world. There is an epidemic created by the huge population of the now-plentiful mosquitoes. The epidemic is only traceable through a protein that could enter live human systems without disrupting them. The green fluorescent protein doctors used to retrieve from jellyfish is the only one that was ever known. This plague brings about the destruction of the human race. Beyond this, we have no knowledge.
The world would not be a pleasant place to live in without jellyfish. Not only are these phantasmal creatures an excellent source of protection, food, and predators, but they also provide human doctors with medicine and scientists with a green fluorescent protein used in following gene translation and protein products in living cells. Even now, these ephemeral beauties have not yet been completely found, for the polyp forms of many lie undiscovered. If jellyfish survived 650 million years, and survive still, they must be doing something right. They deserve our respect and attention, and should not be regarded simply as pests. Though some are deadly, most are not. Even so, there must be a reason why these creatures are so deadly, perhaps it is a response to their prey, or their predators. This is something we should investigate further. Fascinating creatures, they are a unique and exquisite creation of Mother Nature, for there is truly nothing else like them. So next time the call goes out to vilify these elegant, enigmatic phantoms of the deep, raise a voice and dare. Dare to sing the praises of the dreaded jellyfish.
Buchsbuam, Ralph & Associates, Animals Without Backbones. Third Edition, Chicago: University of Chicago Press, 1987.
Campbell, Eileen, Kopp, Kathy, and McCann, Andrea, A Guide to the World of the Jellyfish. Monterey: Monterey Bay Aquarium Foundation, 1992.
Gura, Trish, "Structure of Gene-Tag Protein Solved." Science 1336 (September, 1996).
Amazing Creatures of the Sea, National Wildlife Federation. 1987.
Microsoft Encarta Encyclopedia, "Coelenterates" and "Jellyfish," USA: Microsoft Corporation, 1993.
Morris, Susan. Illustrations. January 1998.
http://www.aqua.org, December 26, 1997.
Less than 1 period.
Supplement a study of biology with an activity drawn from this winning student essay.