| A | B |
|---|
| low tide | the time at which the tide reaches its lowest level. Low tide occurs approximately six hours after high tide |
| mid-ocean ridge | an underwater mountain chain that circles Earth, extending through the middle of most oceans. The Mid-Atlantic Ridge is the portion of the mid-ocean ridge that extends north-south throught the Atlantic Ocean |
| mollusk | a member of the phylum Mollusca, characterized by a muscular foot, an out mantle, and a rasping mouth-like radula. Includes gastropods and bivalves |
| neritic zone | the submerged ocean area that extends from the lowest low-tide line to the edge of the continental shelf. Ninety percent of all marine species live in the neritic zone |
| operculum | a lid or flap that covers the opening in a univalve shell to protect the animal inside from predators or from drying during low-tide exposure to air |
| precipitation | any form of water that falls from clouds in the sky. Rain, sleet, hail, and snow are all forms of precipitation |
| prevailing winds | the global wind systems caused by uneven heating of Earth's curved surface by the sun |
| runoff | water that does not seep into the ground or evaporate but instead flows over Earth's surface. This mineral-rich water often ends up in streams and rivers, which empty into the ocean |
| salinity | a measure of the amount of solids (salts) in ocean water. Ocean water has an average salinity of 3.5 percent |
| sea | a region of ocean water partly enclosed by land |
| seamount | a submerged mountain rising from the ocean floor |
| sonar | the use of acoustic (sound) waves to detect underwater objects and landforms |
