What kind of life survives in Abyssal regions?

Abyssal refers to ‘belonging to the lowest depths of the Oceans. In usual term, the abyssal region has a depth greater than about 4,000 m-but its limit cannot be defined with precision. The sunlight can not penetrate these depths, there is no plain life, but species of animal life, whose nature varies with the depth due to differences in temperature and the supplies of oxygen and food. Much of their food consists of organic matter that sinks from the waters above. Conditions on the ocean floor at these great depths are extremely uniform, perpetually dark while on compression they are more closely packed. On expansion the lowering temperature reaches to Dew-point, causing precipitation and condensation.