Amphioxus

Amphioxus, also known as the lancelet, is a small marine invertebrate belonging to the phylum Chordata. It is a primitive chordate, closely related to the ancestors of all vertebrates. Its small, transparent body makes it an ideal model for the study of vertebrate development. Amphioxus is used to determine the evolutionary relationships between invertebrates and vertebrates, as well as the origins of various features of vertebrate anatomy. Its short-lived life and easy husbandry in laboratories also make it a valuable tool for studying molecular, developmental, and evolutionary biology.