The water jet is a means of propulsion.
they jet through the water at really high speed
This is a very good question. Squids move through the water at high speeds using a jet propulsion-like organ called a "siphon". What the siphon does is take in water and thrust it out, much like a jet engine. The end result is the jet-like streamline of a squid.
Squid move by jet propulsion, using its lips to suck water in then squirts it out its bottom.
No, squids will day if they are out of water for too long.
Sounds like you are talking about octopus and squids which are not mammals.
Octopuses and squids can also move by using a form of jet propulsion. Water is drawn into the mantle cavity and then forced out through a tube, propelling the cephalopods backwards from danger. In addition, squids and octopuses produce a dark-colored ink when the are frightened. As this ink is released into the water, it helps to hide the mollusks/squids/octopuses and confuse its predators
They live in water.
With their tentacles.
They live in water.
They let their water out into the ocean.
Cause they are that cool
Cause they are that cool