Describe the phylum which shows bioluminescence.

(N/A) $\rightarrow$ Bioluminescence,the property of a living organism to emit light,is a well-marked characteristic of the phylum $Ctenophora$.
$\rightarrow$ $Ctenophores$,commonly known as sea walnuts or comb jellies,are exclusively marine,radially symmetrical,and diploblastic organisms with a tissue level of body organisation.
$\rightarrow$ The body bears eight external rows of ciliated comb plates,which help in locomotion.
$\rightarrow$ Digestion is both extracellular and intracellular.
$\rightarrow$ Sexes are not separate (hermaphrodite).
$\rightarrow$ Reproduction takes place only by sexual means.
$\rightarrow$ Fertilisation is external with indirect development.
$\rightarrow$ Examples: $Pleurobrachia$ and $Ctenoplana$.