Abyssal fish are species that inhabit the deep ocean, typically found at depths of 2,000 to 6,000 meters (6,600 to 19,700 feet). These fish have adapted to extreme conditions, including high pressure, low temperatures, and complete darkness. Their bodies often feature unique adaptations, such as bioluminescence, which helps them attract prey or communicate. Many abyssal fish have large mouths and expandable stomachs, allowing them to consume prey that is much larger than themselves. Examples of abyssal fish include the anglerfish and the gulper eel. These fascinating creatures play a crucial role in the deep-sea ecosystem, contributing to nutrient cycling and energy transfer.