The hydrodynamicus is a worse swimmer than the parasite marephasmatis, but is more streamlined, which makes it even easier for it to stay on its host. Not only that, but it also uses a mild stimulus to make the host more cooperative. It even sends out a small cloud of stimulus around itself when endangered or seeking a new host.
Living Relatives (click to show/hide)
These are randomly selected, and organized from lowest to highest shared taxon. (This may correspond to similarity more than actual relation)