Write the general characteristics of phylum Mollusca.

(N/A) $\rightarrow$ Mollusca is the second largest animal phylum.
$\rightarrow$ Molluscs are terrestrial or aquatic (marine or fresh water) and possess an organ-system level of organization.
$\rightarrow$ They are bilaterally symmetrical, triploblastic, and coelomate animals.
$\rightarrow$ The body is covered by a calcareous shell and is unsegmented, with a distinct head, muscular foot, and visceral hump.
$\rightarrow$ The space between the hump and the mantle is called the mantle cavity, in which feather-like gills are present.
$\rightarrow$ These gills perform respiratory and excretory functions.
$\rightarrow$ The anterior head region has sensory tentacles.
$\rightarrow$ The mouth contains a file-like rasping organ for feeding, called the radula.
$\rightarrow$ They are usually dioecious and oviparous, with indirect development.
$\rightarrow$ Examples: Pila (Apple snail), Pinctada (Pearl oyster), Sepia (Cuttlefish), Loligo (Squid), Octopus (Devil fish), Aplysia (Sea hare), Dentalium (Tusk shell), and Chaetopleura (Chiton).