In $Hydra$,both pseudopodia and flagella occur in

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

The most appropriate term to describe the life cycle of $Obelia$ is .....

$A$ coral island with a central shallow lake is known as

In which phylum are neurons present,but nerves are absent?

Coelenterate with a skeleton of $CaCO_3$ is called as: