Starting with Phylum Mollusca(Clam, Squid) through the Phylum Annelida (Earthworm) and the Phylum Arthropoda (Grass Hopper/Grayfish) all the way through the Phylum Chordata(Perch) compare the specimens.
Respiratory organs: what would the appearance of these be in each speciman. Briefly what would the advances noted from one Phylum to another.
Digestive system: What would this look like in each speciman. In brief what would the advances be from one Phylum to another. What would the stomach contents be of the specimens if there are definite observations
Excretory Organs: What would the appearance be of these in each specimen. In brief describe advances noted from one Phylum to another.