6. Deep-ocean biology

Abstract

The deep ocean is currently defined as the water column and ocean bottom greater than 500 metres, which is the depth at which seasonal variation in temperature and salinity and the influence of sunlight is minimal. This habitat encompasses roughly 90 per cent of the ocean’s volume yet this vast region is the least investigated and understood environment on the planet. ‘Deep-ocean biology’ explains that there are many issues for the existence of life in the deep ocean: lack of light, extreme pressure, scarcity of food, and temperature. However, deep-ocean animals have adapted to their surroundings. The diversity of deep-ocean benthic animals is described along with the unique ecosystems found around hydrothermal vents and seamounts.