Hello everyone! I have a college group project I am working on right now where our group designs a hypothetical animal based on fictional planet conditions, and I am running into some issues.

Fitting all the body systems together has been a bit of an issue, because I seem to find a new contradiction every time I settle on something.

Right now I am really stuck on the circulatory system especially. We decided that due to the high UV radiation of our planet and varying extreme temperatures, we will have to have an endoskeleton instead of an exoskeleton so we can have an endotherm.

Originally I was going to settle on an open circulatory system for the benefit of low pressure since our planet has lower pressure too, but I realize now that that is unlikely to support an endoskeleton if I am not mistaken. So now I am looking at closed circulatory system possibilities, but I need to figure out a way to HAVE a closed one without it being too high-pressure.…