The most important distinctive character of $Chordata$ is the presence of

$A$ schematic representation of a chordate's embryo is shown in the figure. The structures marked $A, B, C$ and $D$ are respectively:

To which group does $Salpa$ belong?

The animal that possesses a notochord throughout its life is

Fishes,amphibians,reptiles,and birds are kept in the same

Excretion by protonephridia with solenocytes is a characteristic of