Answer:
lungs and kidneys
Explanation:
The median plane divides the body into two halves through a mid line.
The transverse plain is also known as the axial plane and it divided the body into the upper part and a lower part.
The frontal plane is also known as the coronal plane. It divided the body into the dorsal and ventral sections. The dorsal and ventral sections are the front and back sections ( belly and back).
Lungs and kidneys are the only parts which cannot be seen through all the three plains.
Photosynthesis is the process by which plants use light energy to convert carbon dioxide and water into sugars...Respiration occurs when glucose combines with oxygen to produce useable cellular energy. This energy is used to fuel growth and all of the normal functions.
. I think that bivalves have evolved to have smaller head regions because they have also evolved to have bigger shells or valves than cephalopod
