Underwater Creature

The lack light requires creatures to have special adaptations to find food, avoid predators, and find mates. Most animals have very large eyes with retinas constructed only cones, which increases sensitivity. Many animals have also developed large feelers to replace peripheral vision. To be able to reproduce, many these fish have evolved to be hermaphroditic, eliminating the need to find a mate. Many creatures have also developed very strong senses smell to detect the chemicals released by mates.
Lack Resources
At this depth, there is not enough light for photosynthesis to occur and not enough oxygen to support a fish living at higher levels. To survive, these creatures have much slower metabolisms and therefore can survive using little oxygen. They can also go months without food. Most food comes from either organic material that falls from above or from eating other creatures that have derived their food through the process chemosynthesis (the process changing chemical energy into food energy). Because the sparse distributions creatures, there is always at least some oxygen and food. Also, instead using energy to search for food, these creatures use particular adaptations to ambush prey.