The ocean seabed is one of the most exciting and interesting places on earth. The vast majority of the information we have on the floor of the ocean is newer, as technology that allows us to study the ocean floor developed only a few decades ago. Studying the ocean floor is difficult for multiple reasons. First, the ocean bottom is completely dark. Sunlight only penetrates the ocean surface so far. Because there is no light, the water is very cold – almost freezing. The trillions of trillions of pounds of water make the water pressure extremely heavy, which can crush scientific instruments.

Geography of the Floor

Below the ocean are mountains, volcanoes both active and inactive, trenches and plateaus. Shallow ocean that surrounds land is called the continental shelf. The shelves get to about 600 feet deep until they slope downward suddenly, becoming the continental slopes. These slopes go all the way down until they become what is called the ocean abyss. The abyss is the part of the ocean that contains the most mountains and volcanoes.

How do we know how deep it is? Mapping the ocean floor

A long time ago, sailors would measure the ocean depth by placing a heavy lead rope into the ocean water. The rope would be marked off in fathoms. The depth would be noted by how much line was put out until the weight reached the bottom. These days, to measure-out and map the depth of an ocean, oceanographers use sonar technology. While out at sea on a boat, they send out sonar wave signals which travel all the way to the ocean floor and then echo back to the boat. The speed of sound in water travels much faster than the speed of sound through air, at about 1,500 meters per second. The longer it takes the signal to boomerang back to them, the deeper the ocean is. The deepest ocean trench ever found was in the south part of the Pacific Ocean. It is named the Mariana Trench and is 6 1/2 miles deep!

Benthic Ecosystems

The bottom of the ocean is home to many fascinating animals and plants. More species are being discovered every year. It was once believed that no living organisms could survive without sunlight because without sunlight, photosynthesis is impossible. However, this theory was proved wrong. Since the sun’s energy can only penetrate the ocean’s surface about 1,000 feet, and there are many animals and plants that live far below this, life without photosynthesis is possible, but how? One answer is geothermal vents, more commonly known as hot springs. In the 1970s, scientists found hot springs deep within the ocean near Ecuador. With it, they found a new kind of ecosystem, including various kinds of worms, sponges, sea anemones and shellfish. Ocean floor dwelling life is called "benthic life" or "benthos". Most benthic life is attached to the bottom of the floor or it at least survives off the substrate (a mixture of sand and decomposed fish that have sunk to the bottom of the sea after death.) These creatures also survive off of these warmer volcanic waters, which can sometimes get to be as warm as 380 Degrees Celsius! The basic form of organic life in this ecosystem is a bacteria that live off of hydrogen sulfide gas. H2S is a volcanic gas that is "burped-out" from the inside of the earth.

Bizarre Fish

Because the deep ocean has little to no light, many fish that live in the part of the world have evolved by growing light-emitting organs. The anglerfish is a great example of this. The females have a glowing, rod-like growth that emerges from the spine and bobs above its head. This light lures prey to the angler. The anglerfish’s body is very soft and pliable, allowing it to swallow food whole, up to twice its own size! Usually a dark brown or gray color, deep-sea anglerfish have big heads, enormous mouths, and large, see-through teeth.

Scientists have discovered a creature they named Grimpoteuthis, nicknamed the Dumbo octopus. This soft-bodied octopus has large, elephant ear-like fins that stick out from their head-like bodies. Unlike most octopuses which crawl, dumbo octopuses are pelagic, which means they swim like fish. They gracefully glide across the floor, hovering over it only a few inches, searching for worms and crustaceans to eat whole. The Dumbo octopus can use its tentacles to strangle an enemy if it feels that it is in danger.

Other beautiful but bizarre creatures found deep in the ocean are different types of jellyfish including the crown jelly fish, crystal jellies and flower-hat jellies. Although jellies have no heart, brain, or eyes, their sting makes them one of the major predators of the ocean.