| A | B |
|---|
| Sonar | A system that determines the distance of an object under water by recording echoes of sound waves; gets its name from sound navigation and ranging |
| Continental shelf | A gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent |
| Continental slope | An incline leading down from the edge of a continental shelf (hill) |
| Seamount | A mountain on the ocean floor that is completely underwater |
| Abyssal plain | A smooth, nearly flat region of the deep ocean floor |
| Mid-ocean ridge | The undersea mountain chain where new ocean floor is produced; a divergent plate boundary |
| Trench | A deep canyon in the ocean floor |
| Plankton | Tiny algae that float in water and are carried by waves and currents |
| Nekton | Free-swimming animals that can move throughout the water column |
| Benthos | Organisms that live on the bottom of the ocean or another body of water |
| Food web | The pattern of overlapping food chain in a habitat or ecosystem |
| Intertidal zone | The are that stretches from the highest high tide line on land out to the point on the continental shelf exposed by the lowest low tide |
| Estuary | A coastal inlet or bay where fresh water mixes with salty ocean water |
| Brackish | Water that is partly salty and partly fresh, characteristic of estuaries |
| Neritic zone | The region of shallow water I the ocean that extends from the low-tide line out to the edge of the continental shelf |
| Open-ocean zone | The area of the ocean beyond the edge of the continental shelf |
| Holdfast | A bundle of root-like strands that attaches algae to the rocks |
| Atoll | A ring-shaped coral island found far from land |
| Bioluminescence | The production of light by living things |
| hydrothermal | An area where ocean water sinks through cracks in the ocean floor, is heated by the underlying magma, and rises again through more cracks |
| Aqua culture | The farming of saltwater and freshwater organisms |
| Nodule | A black, potato-shaped lump- formed when metals such as magnesium form around pieces of shell on the ocean floor |
