What is present between the two germ layers in the phylum $Cnidaria$?

Which of the following animals has a tetramorphic colony?

"Portuguese man-of-war" is a/an:

Hydra recognizes its prey by

Which of the following statement$(s)$ is/are correct regarding phylum $Coelenterata$ (Cnidaria)?
$(A)$ They are aquatic,mostly marine,sessile or free-swimming,radially symmetrical animals.
$(B)$ They have a central gastro-vascular cavity with a single opening on hypostome.
$(C)$ Digestion is extracellular and intracellular.
$(D)$ Their members are $Sycon$,$Spongilla$ and $Euspongia$.

$A$ radially symmetrical,diploblastic animal is: