Upwelling: The movement of nutrient-rich water from a specified depth to the surface.
Water mass: A body of water that maintains its physical identity and can be characterised by parameters such as temperature and salinity.
Xenophyophores: Large single-celled organisms, that are common throughout the deep-sea. They are small fragile organisms often no larger than a golf ball, which may resemble flattened discs, angular four-sided shapes or spheres.
Zooplankton: Tiny animals with limited ability to move, which usually drift with water currents. Includes small crustaceans and larvae of many larger animals.