By Dr. Alan Jamiesson, Oceanlabs Aberdeen

The Deep Ocean is by far the largest habitat on Earth and yet it remains the most poorly understood. Ever since man has dared to explore this unfamiliar environment, more questions have arisen than have been answered - a trend that seems set to continue.

The deep sea realm is characterised by low temperatures, high hydrostatic pressures and the absence of solar light. Furthermore, the mid-water (Pelagic) environment has a vertical dimension unlike anywhere else. Even so, this seemingly inhospitable three-dimensional setting is home to extraordinarily diverse and enigmatic creatures. The deep-pelagic zone has become synonymous with an ‘alien’ environment, and deservedly so.

The inhabitants of the deep-pelagic zones have evolved the most imaginative and often the most bizarre adaptations for survival. In the darkest depths, light becomes an extremely important commodity and thus the ability to use biologically-produced light can be highly advantageous for certain species. Some species use light lures to entice smaller prey towards gaping mouths, while others use biological light to camouflage themselves or simply display light to disorientate predators. Whether light is used for communication, reproduction, defence or offense, the production of light where there is none can mean the difference between life and death.

Many deep-sea species are highly cryptic in appearance: the males and females of some species look nothing alike and in others there are no similarities between juveniles and adults. There are even some species where reproduction involves the absorbing of a tiny male by the larger female. Whatever the adaptation, whether physical or strategic, it will undoubtedly be exploited by one creature or another in the deep sea.

Despite the extreme depths and remoteness of the deep-sea environment and its inhabitants from land-dwelling humans, inhabitants of the deep sea are not exempt from anthropogenic disturbance and effects of a changing climate. Conservation efforts rely heavily on knowledge of biodiversity, ecosystem function and the roles of each species therein. Difficulties with sampling and monitoring the inhabitants of these extreme depths mean that detailed knowledge concerning all of these factors is lacking. Through detailed exploration of the deep sea, modern science is currently trying to fulfil the obligation to ultimately improve our understanding of this realm in order to secure and conserve one of the most enigmatic habitats that the Oceans have to offer.