This… is creepy… haha

Creepy and gross and inventive to write from the viewpoint of this parasite. A bit inconsistent though as you have it look for the gap in the spine, then ignore that and swim around the peritoneal space from which it thinks it sees the lungs, which you can’t see from in there. Next the tail stuck out, then it swims around.

So you’ve got a neat idea, it just wound up a little all over the place and not anatomically correct, per se.