Which animal possesses neurons but lacks a brain?

In $Hydra$,both pseudopodia and flagella occur in

It is a common cavity that performs both digestive and circulatory functions.

Mesogloea is present in the Phylum

These animals exhibit tissue-level organization,are diploblastic,and show radial or bilateral symmetry.

Identify the correct features for $Medusa$ and $Polyp$ forms in Phylum $Coelenterata$ (Cnidaria) from the given list:
$I$ - $Sessile$
$II$ - $Umbrella-shaped$
$III$ - $Free-swimming$
$IV$ - $Produced$ $by$ $asexual$ $reproduction$
$V$ - $Cylindrical$
$VI$ - $Produced$ $by$ $sexual$ $reproduction$
$Medusa$ $\quad\quad$ $Polyp$