Suckers on the tentacles of the giant squid, Architeuthis dux, the creature with the largest eyes on Earth.
Because so little is known about the deep sea, compared to habitats on land, scientists are continually discovering new things - some of them very surprising. Here are some facts from the deep ocean.
The oceans cover two-thirds of the Earth's surface to an average depth of almost 4km. The deepest point discovered so far is almost 11km deep.
The oceans provide about 190 times as much living space as all of the Earth's other environments - soil, air and fresh water - put together.
Life on Earth almost certainly originated in the sea and was more or less restricted to the oceans for the first 3 billion years of evolution.
The giant squid, Architeuthis dux, has the largest eyes of any animal on Earth. They are up to about 30cm across - the size of a dinner plate.
The record for the deepest fish goes to Abyssobrotula galatheae, a member of Ophidiidae family. It was dredged from the bottom of the Puerto Rico Trench at a depth of 8,368m in 1970.
The largest known deep sea fish is the Greenland shark, Somniosus microcephalus, which grows to over 7m in length. However, it doesn't spend all its time in the deep sea. It also comes up to the surface to eat offal thrown overboard from fishing boats.
Life in the sea is incredibly rich. There are creatures from 28 major groups of animals living in the sea, including sponges, crustaceans and molluscs, whereas only 11 major groups of animals live on land.