characteristics that unify mollusca
I. Unifying Characteristics. 1  80,000 species total (2nd largest phylum, Arthropods come first). 2  Body of Foot, Visceral Mass, Mantle and Shell (exoskeleton). 3  Mouth with Radula.4  Protostomes, Bilateral, Tripoblastic, Reduced Coelom. 5  Respiratory by gills or lungs. 6  Sexes separate usually.. Unifying Characteristics. 1  80,000 species total (2nd largest phylum, Arthropods come first). 2  Body of Foot, Visceral Mass, Mantle and Shell (exoskeleton). 3  Mouth with Radula. 4  Protostomes, Bilateral, Tripoblastic, Reduced Coelom. 5  Respiratory by gills or lungs. 6  Sexes separate usually.