Notes

1. hydrothermal vent - fish that glow in the dark live here, worms hang out here, a very unusual ocean feature, deep-sea hot springs along ocean ridges
2. many varieties of organisms live in a vent community
3. The neritic zone extends from the intertidal zone to the edge of the continental shelf.
4. The oceanic zone begins at the edge of the continental shelf and stretches out into the open ocean.
5. The neritic zone is made up of the water that covers the continental shelf, so at most it's about 200 meters (656 feet) deep. These waters have some light, except in the deepest parts.
6. The neritic zone is bright, so lots of phytoplankton live here. Phytoplankton are tiny, plant-like organisms that make their own food by photosynthesis. With lots of phytoplankton for other organisms to eat, an active food web exists here. Many small fish and invertebrates live in the neritic zone. So do larger fish, such as cod and mackerel.
7. Organisms that swim are called nektons. These include bony fish, sharks, rays, whales and dolphins, among others. But the majority of organisms in the open ocean are plankton. Plankton have little say about where they go. In other words, they simply drift or move about in a very small area.
8. intertidal zone
9. abyssal zone
10. In the upper oceanic zones, plankton drifts along with the current. Below that, from about 200 meters to 1,000 meters (656 to 3,280 feet), is a twilight zone, too dark for photosynthesis. Some whales swim in this strange zone of half light. So do many kinds of fish.
11. Even farther down is a zone about 1,000 to 4,000 meters (3,280 to 13,280 feet) deep. Here, almost no light gets through. Called the midnight zone, this is the kingdom of giant squid and many kinds of fish with bioluminescent body parts--parts that glow in the dark.
12. Below 4,000 meters is the abyssal zone. Almost half the fish in this zone are bioluminescent. The abyssal plain is the final resting place for marine snow, the term scientists use for all the dead organisms, sand, dirt, minerals, and other things that sink through the water to the plains below. Drag the slidebar with your mouse to see different depths.
13. As you go deeper, the water gets colder and colder, but all the way at the bottom is something very unusual--hydrothermal vents. The word thermal implies heat, so you might guess that these are hot areas. In deep areas near mid-ocean ridges, lava oozes out through cracks in the ocean floor. Water temperatures here range from 35 to 700° C (95 to 1,300° F). A rich mixture of chemicals are the source of energy for some unusual organisms that live here. These chemicals provide the energy for life in a sunless sea.
Specialized bacteria, crabs, limpets, and strange tubeworms live here. One fish, the pink bathitid, is adapted to live with its head down in the vents for most of its life. Life near vents is very rich. Scientists say it might even be as diverse as a tropical rain forest.
14. Imagine the surprise of the first scientists who saw what appeared to be smoking chimneys at the bottom of the ocean! These chimneys are hydrothermal vents. Some are taller than a 15-story building. Out of their tops flow underwater columns of what looks like black smoke.
15. Organisms on Earth depend on the sun for energy, but in the deep parts of the ocean, creatures are adapted to darkness
16. Red worms eight feet long, giant clams, and blind fish live down deep where the water is warmer but the pressure is almost 300 times greater than at sea level