| A | B |
|---|
| invertebrate | an animal lacking a backbone or spinal column |
| low tide | the time at which the tide reaches its lowest level. Low tides occurs approximately six hours after high tide |
| mid-ocean ridge | an underwater mountain chain that encircles Earth, extending through the middle of most oceans. The Mid-Atlantic Ridge is the portion of the mid-ocean ridge that extends north-south through the Atlantic Ocean |
| precipitation | any form of water that falls from clouds in the sky. Rain, sleet, hail, and snow are all forms of precipitation |
| runoff | water that does not seep into the ground of 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 aveage salinity of 3.5 percent |
| seamount | a submerged mountain rising from the ocean floor |
| surface current | a type of ocean current caused by the friction of prevailing winds moving across the surface of the ocean. Surface currents are located in the upper 100 to 200 meters of ocean water |
