$A$ fish differs from a whale in having

Which marine animals possess a notochord only during their larval stage?

$Herdmania$ belongs to which subphylum?

Select the correct option for the following matches regarding Chordates:

$(1)$ Notochord present only in larval stage.	$(a)$ Chordata
$(2)$ Notochord present throughout life.	$(b)$ Vertebrata
$(3)$ Notochord is replaced by vertebral column.	$(c)$ Cephalochordata
$(4)$ Notochord is mesodermal in origin.	$(d)$ Urochordata

Select the correct statements with reference to chordates.
$A$. Presence of a mid-dorsal,solid and double nerve cord.
$B$. Presence of closed circulatory system.
$C$. Presence of paired pharyngeal gill slits.
$D$. Presence of dorsal heart.
$E$. Triploblastic pseudocoelomate animals.
Choose the correct answer from the options given below:

In some chordates,the notochord is replaced by the vertebral column. Such animals are called vertebrates. Which one of the following statements is correct?