The giant squid, or Architeuthis dux, is among the least seen and studied creatures of the sea. No live giant squid was even seen in its natural habitat until 2006. The giant squid, which can get as big as 70 feet long when most squids top out a 12 inches, is attached to many myths. In truth, it has just adapted to life in the deep ocean where light is very limited.
Giant squids have eyes as big as 10 inches wide. The large retinas allow the animals to gather a great deal of light. The eyes are also capable of seeing the luminescent lights produced by some creatures in the dark depths of the ocean. The squid can likely get to that kind of prey faster than other creatures.
It's not quite jet propulsion, but the giant squid does use a similar system to get around. It sucks water into a funnel in its mantle, the main part of its body. This water is then forced back out again, and the squid uses the force of that action to propel itself in one direction. The more water it takes in at once, the faster it will go when the water is forced out. This action also gathers oxygen as the water is passed through its gills.
Arms and Tentacles
Giant squids have eight arms and two tentacles. A mature giant squid can measure up to 33 feet from the top of its head to the bottom of its arms. It can get even longer when it extends its tentacles. Both appendages draw prey in towards the animal’s mouth, but only the tentacles are also used to catch prey. Suckers line the inside of the appendages. These suckers have sharp, rough edges that can attach themselves to the animal’s food and cut into it if necessary. It typically draws the food into its beak, which is sharp enough to crush any prey. As of 2011, the giant squid's actual diet is unknown since none had been caught with food in it. Based on its beak, it likely pursues fish and smaller squids.
A jet of dark ink is the first line of defense for the squid. It stands to reason that they can use jet propulsion to escape from a predator quickly, and apparently fight with the suckers on the tentacles too. It is known that giant squids are preyed upon by whales since beak remains have turned up in whale stomachs. The skin of sperm whales sometimes shows sucker marks that could only have come from a desperate giant squid.