Why Do Deep Sea Creatures Evolve Into Giants?

The term deep sea creature refers to animals that live below the photic zone of the ocean. These creatures must survive in extremely harsh conditions, such as hundreds of bars of pressure, small amounts of oxygen, very little food, no sunlight, and constant, extreme cold.
NASA, to their amazement, has discovered vibrant ecosystems around the vents, teeming with marine organisms.
Some of the animals living in the deep ocean include pelican Eel, Goblin Shark, Seadevil Angelfish, Deep-sea Octopus, Deep-sea Dragonfish, Zombie worms, and many more.
This documentary takes a look at some of the marine animals living in the deep sea, and how they evolve into gigantic creatures over time.