| A | B |
|---|
| sonar | a system that uses sound waves to calculate the distance to an object, which gets its name from sound navigation and ranging (p.149( |
| seamount | a mountain on the ocean floor that is completely underwater (p.151) |
| trench | a deep canyon in the ocean floor (p.152) |
| sea-floor spreading | the process by which new material is added to the ocean floor along the boundary between diverging plates (p.154) |
| continental shelf | a gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent (p.150) |
| abyssal plain | a smooth, nearly flat region of the deep ocean floor (p.151) |
| magma | hot, liquid substance that makes up part of Earth's mantle (p.153) |
| continental slope | a steep incline leading down from the edge of the continental shelf (p.150) |
| mid-ocean ridge | the continuous range of mountains on the ocean floor that winds around Earth (p.151) |
| plates | the major pieces that make up Earth's upper layer (p.153) |
| plankton | tiny algae and animals that float in water and are carried by waves and currents (p.157) |
| food web | the feeding relationships in a habitat (p.157) |
| brackish | water that is partly salty and partly fresh, characteristic of estuaries (p.160) |
| nekton | free-swimming aimals that can move throughout the water column (p.157) |
| intertidal zone | the area that stretches from the highest high-tide line on land out to the point on the continental chelf exposed by the lowest low tide (p.158) |
| benthos | organisms that live on the bottom of the ocean or other body of water (p.157) |
| estuary | a coastal inlet or bay where fresh water from rivers mixes with salty ocean water (p.160) |
| neritic zone | the part of the ocean that extends from the low-tide line out to the edge of the continental shelf (p.163) |
| holdfast | a bundle of rootlike strands that attaches algae to the rocks (p.164) |
| bioluminescence | the production of light by living things (p.167) |
| atoll | a ring-shaped coral island (p.164) |
| hydrothermal vent | an area where ocean water sibnks through cracks in the ocean floor, is heated by the underlying magma, and rises again through the cracks (p.168) |
| aquaculture | the farming of saltwater and freshwater organisms (p.171) |
| nodules | lumps formed when metals such as manganese build up around pieces of shell on the ocean floor (p.171) |
