Anglerfish

• Anglerfish live up to a mile below the water's surface in the Atlantic and Antarctic oceans. These angry-looking creatures have large crescent-shaped mouths filled with sharp teeth. Anglerfish are typically dark gray or brown in color and grow between the lengths of 8 inches and 3.3 feet. When full grown, they can weigh up to 110 lbs. Anglerfish get their name from their most distinctive feature, a piece of dorsal spine that originates from the top of the head and hangs out in front of the mouth, similar to a fishing pole. Like the rest of an anglerfish's body, the extended spine glows with the help of bioluminescent bacteria. This baits prey into becoming the anglerfish's next meal.
  
  

Viperfish

• The viperfish is a deep sea animal usually found in 5,000 feet of water. Like the anglerfish, the viperfish also has a large mouth and fanglike teeth. The dorsal spine of the viperfish runs the length of the body and emits light through an organ known as a photophore. The photophore flashes light in an attempt to draw prey near; smaller fish are then impaled and killed by the sharp teeth of the viperfish. Viperfish only grow to about 12 inches long and are silvery blue in color. They can go for days without food because of their low basal metabolic rates. Scientists believe the scarce nature of food in the deep sea has something to do with this.
  
  

Giant Squid

• The giant squid is the largest invertebrate on Earth. For hundreds of years, scientists had never seen or photographed a giant squid alive. Washed-up carcasses were the only proof that they even existed. Deep sea habitats are believed to be the reason for their elusive existence. In 2004, a team of Japanese researches took the first pictures of a living giant squid. In 2006, they were able to catch one and bring the 24-foot creature to the surface alive. The longest giant squid ever to be washed ashore measured 59 feet in length and weighed nearly a ton. Like normal squid, giant squid have eight arms and two feeding tentacles. Their diet is believed to consist of fish, shrimp and other squid. Seafaring folklore suggests that these large invertebrates even attack and eat small whales.
  
  

Giant Tube Worms

• Giant tube worms are a rare specie found only near hydrothermal vents on the Pacific Ocean floor. These vents have an average depth of about 5,000 feet. Hydrothermal vents are powered by volcanic heat and circulate water that seeps into cracks or faults. When the water emerges from a hydrothermal vent, it is usually rich in minerals and chemicals. Giant tube worms thrive because of a process known as chemosynthesis; they feed on bacteria and get their energy directly from the chemicals in the boiling hydrothermal water. Giant tube worms are typically red and can reach 8 feet in length. They do not have mouths or digestive tracts. Instead, they depend on bacteria that lives inside of them to convert hydrothermal chemicals into organic molecules of food.