Give the general characteristics of phylum Porifera.

(N/A) $\rightarrow$ Phylum Porifera (Latin: porus = pore, ferre = to bear) includes the first and most primitive group of multicellular animals, commonly referred to as sponges.
$\rightarrow$ They are primitive, multicellular animals with a cellular level of organization.
$\rightarrow$ They are generally marine and mostly asymmetrical.
$\rightarrow$ Sponges possess a unique water transport or canal system.
$\rightarrow$ Water enters through minute pores (ostia) in the body wall into a central cavity, the spongocoel, from where it exits through the osculum.
$\rightarrow$ This pathway of water transport is essential for food gathering, respiratory exchange, and the removal of waste products.
$\rightarrow$ Choanocytes or collar cells line the spongocoel and the canals.
$\rightarrow$ Digestion is intracellular.
$\rightarrow$ The body is supported by a skeleton made up of spicules or spongin fibres.
$\rightarrow$ They are hermaphrodite (sexes are not separate), and reproduction occurs both asexually (by fragmentation) and sexually (by formation of gametes).