Due to the difficulty of deep sea challenges life has had to adapt and is very diverse in deep sea ecosystems, destruction may be occurring to life that we haven't even had a chance to discover yet; summary points:
The deep sea ecosystem has to cope with: 1) eternal cold, 2) darkness, 3) high pressure and 4) scarcity of food.
Life has adapted to the deep sea ecosystem:
with changes in color: transparency or blackness in color makes it difficult for predators to see prey or to be seen by prey.
Feeding is more likely to be carnivorous in species such as sponges that are typically filter feeders in areas where phytoplankton is prevalent.
Bioluminescence is used to attract prey or to communicate among species.
Mating may involve a permanent coupling of the male to the female of the species.
Very large size and
longer life spans with slow growth and movement is more common in deep sea species.
Thermal vents in the deep sea have even more extreme conditions with very high heat and chemicals that would be toxic to typical life. Bacterial adaptations make the thermal vent ecosystem possible by creating food out of the thermal vent nutrients and detoxifying some of the more toxic chemicals.
Symbiosis with bacteria that can utilize nutrients from thermal vents by chemosynthesis supports the trophic levels around thermal vents by directly providing nutrients to the lower level species with the symbiotic relationship and as prey for higher trophic level species.
Human threats for the deep sea ecosystem include: 1) waste disposal, radioactive, plastic and other waste, 2) deep sea fishing, 3) deep ocean drilling and 4) climate change.
From medicines to rare minerals the deep sea is a treasure trove of life that we are only beginning to explore in more detail. Proteins involved in bioluminescence were studied and are now essential tools for studying cell and microanatomy of the brain and other areas of physiology.
Methods for deep sea fishing or drilling often destroys habitats and species that are hundreds to thousands or more years old. We can't explore or utilize what is destroyed. Bulldozing forests to catch a few wild animals or birds is not good for the forest or useful to humans over the long term however that is what deep sea fishing and mining often accomplishes - a small gain amid destruction of a rare environment.
For more information and images of deep sea life see the video Lecture 5.3 "Life in the Deep Sea," by Ute Hentschel Humeida, GEOMAR, Helmholtz Centre for Ocean Research Kiel and Kiel Univrsity, Germany, One Planet-One Ocean, OC001 Courseware, edX.org , free online course with a small fee if a certificate is desired and earned with a passing grade.