Which set of animals are included under protochordates?

Step-by-step solution

Subphyla Urochordata and Cephalochordata are often referred to as protochordates and are exclusively marine. In Urochordata, the notochord is present only in larval tail, whereas in Cephalochordata, it extends from head to tail region and is persistent throughout their life. Examples: Urochordata: Ascidia, Salpa, Doliolum ; Cephalochordata: Branchiostoma (Amphioxus or Lancelet).