| A | B |
|---|
| sonar | a system that uses sound waves to calculate the distance to an object |
| continental shelf | gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent |
| continental slope | steep incline of the ocean floor leading down from the edge of the continental shelf |
| abyssal plain | smooth, nearly flat region of the deep ocean floor |
| mid-ocean ridge | continuous range of mountains on the ocean floor that winds around Earth |
| trench | deep, steep-sided canyon in the ocean floor |
| intertidal zone | area that stretches from the highest high-tide line on land out to the point on the continental shelf exposed by the lowest low tide |
| neritic zone | area of the ocean that extends from the low-tide line out to the edge of the continental shelf |
| open-ocean zone | deepest, darkest area of the ocean beyond the edge of the continental shelf |
| plankton | tiny algae and animals 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 other body of water |
| food web | feeding relationships in a habitat |
| estuary | coastal inlet or bay where fresh water from rivers mixes with salty ocean water |
| atoll | ring-shaped coral reef that surrounds a shallow lagoon |
| bioluminescence | production of light by living things |
| hydrothermal vent | area where ocean water sinks through cracks in the ocean floor, is heated by the underlying magma, and rises again through the cracks |
| aquaculture | farming of saltwater and freshwater organisms |
| nodule | lump on the ocean floor that forms when metals such as manganese build up around pieces of shell |
