Karen Sotson, age 12, of Hayesville, North Carolina, for her question:
How deep do fish live in the ocean?
The salty sea is populated from its sunlit surface right down to the depths of its deep abyss. Its plants must live within reach of the sunbeams. But certain animals are adapted to endure the hardships of pressure and eternal midnight that exist several miles below the sparkling waves.
The fishes rate as rather advanced members of the animal kingdom. They have backbones and neat bony skeletons. Their scaly bodies are streamlined for expert swimming and many types swarm in teeming crowds through the surface waters. Scientists have classified some! 20,000 of them as True fishes and we tend to think that the salty sea belongs to them and to them alone. They ark, however, outnumbered by other forms of marine life. With various types of fish, they share the wavy roof of the sea, the upstairs, and the lower downstairs level and also the dark depths of the ocean's basement.
We know that certain types of true fishes live at levels of six miles or more below the surface. The bathyscaph sea probe dipped into the Marianas Trench and its viewers spotted a strange
looking flatfish. The depth was 35,800 feet. A deep sea rattail fish was dredged up from a depth of 23,400 feet in the Sunda Trench off Java. Another specimen was brought up from 24,800 feet by scientists exploring the bed of the northwest Pacific.
Certain crustaceans called amphipods and isopods frisk almost everywhere on the deepest sea beds. They share the ocean's dark, dismal basement with brittle stars and sea cucumber cousins of the starfish, with snails and a vast assortment of strange marine worms. Many of these deep sea dwellers are equipped with colored lights and buttons that glow like cold gems in the abysmal darkness.
The wave tossed surface glitters with sparkling sunbeams and the waters are thronged with floating seaweeds and assorted marine creatures. But deeper water filters days from the sunbeams and its pressure grows greater with depth. The sunlit surface dips no deeper than 200 to 300 feet. The level below fades to dingy green and then to dark, violet blue. The pressure increases to 500 pounds per square inch more than 30 times heavier than normal air pressure. Things get worse as we go deeper fish in ocean
No light ever reaches the levels below about 2,000 feet. The creatures that inhabit. the deep regions of eternal midnight are often vividly colored and fitted with fantastic lights. Their bodies are adapted to withstand the immense pressure of water above them. Some have air sacs that expand and explode when their bodies are brought up to the surface. Creatures that live at levels from 18,000 to 35,000 feet must be built to withstand normal pressures of four to eight tons per square inch. Under lighter pressure, their bodies explode. Most of the deep ocean fishes are weird little monsters with huge toothy jaws and expandable stomachs. Big meals are few and far between.
As a rule, the fishes of the deep oeean are seen only by marine biologists. Only a few are well enough known to have non scientific names. The assorted rattails range from an inch to 20 inches in size. Their standard shape is a teardrop with a toothy, shovel shaped jaw. The bulky head tapers to a long ratty tail. The two foot dragonfish resembles an underfed dragon. The sneaky anglers have lines and lures to catch other fish and the sea pelican mouth is a rubbery two foot bag with a pair of trapdoor jaws to fill it.