I'm amazed at Oar Fish, that are very big and very long, and apparently just hang vertically in the water column. They can go up and down very fast but not side-to-side. They feed by hanging under their prey and then move up from below to attack. Their bodies are so long and thin that they have no lateral rigidity.
https://edgedavao.net/wp-content/uploads/2017/02/Oarfish-2.j...
Sailors used to think they were sea serpents.