Dissection Club - Octopi

The mantle is like a pouch that is open on the underside.  Water is taken in and squirted out to provide propulsion.

Just where the tentacles are attached is the mouth which contains the beak.  The beak is the only tough material in this soft bodied animal.  It is used to lever open bivalves.

Underneath the mantle can be found the heart, reproductive organs and in this case, egg, as seen here.