how many species of polyplacophora are there
Chitons are primitive marine molluscs in the class Polyplacophora (formerly the class Amphineura). There are 900 to 1,000 living species of chitons. Their size ranges from 0.5 to 30 cm in length; most are quite small. All the living species are in the subclass Neoloricata, and so may be called 'loricates'. Popular names are sea cradles or coat-of-mail shells.