I really need help with this assignment, i need to know the processes of the digestive, respiratory and circulatory systems?

Please help!

I found one place that said they have an open circulatory system, and another place said closed. I have tried to go by what I know about circulatory systems to match the whaleshark but either sound possible.
Could somebody please verify?
Thankyou.

there are open and closed circulatory systems for different organisms, but on all research sites all they say is that amoebae do not have a circulatory system, yet an amoeba uses diffusion. Isn’t diffusion a trait of an open circulatory system?

i.e. squid & octopus have closed circulatory system
and clams and oysters have open circulatory systems.

What is the name of the disease in which the skeletal and circulatory systems of the individual are clearly visible? I ask this because I know someone who appears to be very anorexic, having very little (or no) body fat, and a slightly arched back. I have heard something about not being able to digest glucose or something, but this has not been verified and may not be legitimate.