The common bath sponge belongs to the genus

Sponges are multicellular,yet they exhibit a cellular level of organization because ..........

Sponges reproduce by

Which one of the following statements about all the four of $Spongilla$,leech,dolphin and penguin is correct?

$Proterospongia$ is a connecting link between:

Body having meshwork of cells,internal cavities lined with food filtering flagellated cells and indirect development are the characteristics of Phylum