| A | B |
|---|
| swim bladder | a balloon-like organ inside a fish that enables the fish to control its buoyancy |
| tides | the alternating rise and fall of the surface level of the ocean, caused primarily by the gravitational pull of the moon on Earth |
| trench | a deep canyon in the ocean floor. Trenches are the deepest crevices on Earth's surface |
| trough | the valley, or lowest point, between the crests of two successive waves |
| univalve | a mollusk having a shell consisting of a single piece, usually spiral or cone shaped |
| vertebrate | an animal with a backbone or spinal column |
| warm-blooded | having an internal body temperature that stays at a relatively constant level. Mammals and birds are examples of warm-blooded animals |
| water cycle | the continuous circulation of water - through evaporation, condensation, and precipitation-between Earth's surface and the atmosphere |
| wave height | the vertical distance between a wave crest and the subsequent trough |
| wavelength | the horizontal distance between two successive waves crests |
