body wall encloses a cavity (spongocoel).water enters through pores (ostia) and goes out through an osculam , by the action of flagellated cells (collar cells / choanocytes)
BecauseB-f bonds are oriented at an angle of 120° to each_other , the three moment gives a net sum of zero . As a resultant of any two is equal and opposite to the third
The theorem states that, the moment of inertia of a body about any axis is equal to the sum of moment of inertia of a body about parallel axis ,passing through centre of mass. And product of mass of the body and the square of the distance between the two axis