(a) Identify the organism in the following figure.
(b) Label the parts numbers 1 to 4.
(c) Name the phylum in which notochord is present.
(d) Name the subphylum in which notochord is present throughout life.

(a) The given figure represents Amphioxus (Branchiostoma).

(b) In the given figure,
1 - represents nerve cord
2 - represents notochord
3 - represents atriopore and
4 - represents oral hood

(c) Organisms belonging to the phylum Chordata have notochord.

(d) Organisms of the subphylum Cephalochordata retain notochord throughout their lives.