Nature’s Submarines and Bathyscaphes
“Our pride in man’s latest discoveries must be tempered by the knowledge that other animals may have been using them from time immemorial.”—Scientific American, July 1960.
“His invisible qualities are clearly seen from the world’s creation onward, because they are perceived by the things made, even his eternal power and Godship.” (Romans 1:20) Surely, Jehovah God’s purposeful wisdom is revealed in these buoyant marine animals.
● THE CHAMBERED NAUTILUS. The nautilus was submarining untold thousands of years before man was even on the earth to daydream of such a wonder. From babyhood it makes its own house, adding on larger rooms as it grows. It partitions off the vacated ones left behind, until its beautiful shell has spiraled outward to some ten inches in diameter. Most of it is decorated with shiny brown zebralike stripes, and in the latest and largest room that opens out on the sea the nautilus lives. In its wake it may have left behind 30 or more chambers, former residences from younger days. But each time the nautilus moved to new, larger quarters, it left behind a part of itself—a tubelike siphuncle (Latin for “little pipe”). And each time the nautilus partitioned off a chamber, it left a small hole in the partition. Through these openings the siphuncle, a siphonlike extension of the nautilus, threads its way through the chambers, all the way back to the first tiny compartment. It is these compartments and the siphuncle passing through them that give the nautilus its submarining abilities. The chambers serve as flotation tanks. They are filled with gas. The siphuncle passing through them can add water, or it can remove water. It can vary the gas/water ratio and thus change the buoyancy. Thus the nautilus can be near the surface or two thousand feet deep, or float anywhere in between.
● THE CUTTLEFISH. The common cuttlefish is found in the Mediterranean and eastern Atlantic waters. A large specimen may have a body two feet long, its eight arms reaching out another ten or twelve inches, and additionally, two long tentacles may shoot out beyond these arms to grab food items. For locomotion it has elongated fins along the sides of its body, plus a funnel, or siphon, that provides jet propulsion. Like the chambered nautilus, it has a submarinelike mechanism for varying its buoyancy. But unlike the shell chambers of the nautilus, the cuttlefish’s buoyancy mechanism is made of bone, the cuttlebone. It is located just under the skin along the back of the cuttlefish. It is a soft, chalky structure, having up to a hundred thin plates held apart by pillars, and honeycombed with many separate chambers. It is this bone that serves as the cuttlefish’s buoyancy tank. As the cuttlefish grows and gets heavier, more chambers are added to the cuttlebone to increase its powers of buoyancy. (Incidentally, it is this cuttlebone that is put in the cages of birds.) By a process of osmosis the cuttlefish can pump water out of the cavities of its cuttlebone or allow water to enter. In this way it varies its buoyancy to ascend or descend in the ocean. In principle, the cavities in its cuttlebone are like the water tanks of a submarine. Cuttlefish usually stay from 100 to 250 feet deep but can descend to 600 feet.
● THE DEEP-SEA SQUID. This giant squid may be the source of the legendary tales of sea monsters that grab ships in their tentacles. Bodies over 10 feet long have been found—with tentacles included, 65 feet! For animals, its eyes are the largest known—16 inches across! It moves swiftly by jet propulsion. It, like the nautilus and the cuttlefish, can adjust to different depths in the sea but does it differently. The upper two thirds of its body is a large cavity, the coelomic cavity. It is filled with a liquid. If this liquid is removed, the squid sinks. The fluid gives the animal its neutral density to seawater. Analysis has shown that it has a very high concentration of ammonia, 1.2 ounces per gallon. Why is this so? Unlike mammals, the squid excretes its nitrogenous wastes as ammonia instead of urea. This ammonia diffuses from the bloodstream into the fluid of the coelomic cavity, where it dissociates into ammonium ions. These ions are lightweight and make the fluid lighter than seawater, imparting buoyancy to the squid. Scientific American magazine compares it with Auguste Piccard’s bathyscaphe that descends into the ocean depths. The bathyscaphe’s large chamber filled with gasoline, which is lighter than seawater, supports the observation chamber suspended below it. Similarly, the coelomic cavity fluid of the deep-sea squid serves as a flotation device. But the squid did it first, because its Creator thought of it first.
● THE SWIM-BLADDER FISH. Many fish have swim bladders filled with gas. When the fish descends, the pressure of the water compresses the gas and reduces the size of the swim bladder. If the fish rises, the water pressure lessens, the gas expands, and the size of the bladder increases. When the size of the bladder changes, so does the size of the fish. So when it descends, increased pressure decreases its volume, which means its average density increases, and this lessens its buoyancy. When it rises, its volume increases, which lessens its average density, and this increases its buoyancy. Thus the swim bladder functions to keep the density of the fish equal to the density of the seawater around it, enabling the fish to float at any depth. But it is not always that simple. At a depth of 6,500 feet, pressure has squeezed the bladder’s volume down to only 1/200th of its volume at the surface, the gas in it is 200 times denser, and buoyancy has about disappeared. Yet fish hover motionless at twice that depth, the gas in their swim bladders exerting a pressure of more than 7,000 pounds per square inch to withstand the pressure of the sea! Yet how do they retain buoyancy? Very slowly they can add gas to their swim bladders as they go deeper and resorb it as they rise. But how can fish in the depths add gas to the bladder when the pressure in it is already so great? No answer. The mechanism of this gas pump is still an enigma.