Animals survive along the deeper sea floor by adapting to the lack of light & the scarce availability of food.
Many of the organisms that live on the sea floor thrive by eating decaying organic matter or synthesize their own food through symbiotic relationships with chemosynthetic bacteria along thermic vents.
Those that don't live on the sea floor use bioluminescence or detect vibrations in the water to catch theyr prey.
Organisms that live deeper in the ocean will typically have slower metabolism & depend less on visual stimuli for finding food.
Hope that helps!