The second largest phylum of the animal kingdom is .........

The most active animal among the phylum $Mollusca$ is ........

Open type of blood vascular system,presence of auricle and ventricle,and presence of haemocyanin respiratory pigment are the characters of

The structural component of the shell in Mollusca is: ............

In $Mollusca$, the feather-like gills are located in the:

Scaphopoda are commonly called