Cuttlefish is a member of which phylum?

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

The study of molluscan shells is known as:

In $Octopus$,$Sepia$,and $Loligo$,the arms are ..........

In some molluscs,the rasping organ for feeding is called .........

The elephant tusk shell is: