The Florida lancelet Branchiostoma floridae is a representative of the invertebrate subphylum Cephalochordata. Lancelets, along with tunicates, are members of the chordate phylum, and share the same basic body plan as vertebrates. This includes a stiffening structural rod, or notochord, a dorsal hollow nerve tube, segmented muscle blocks and pharyngeal gill slits. However, they have a simpler anatomy and physiology than vertebrates, with fewer distinct tissue types and organs. Anatomical, embryological and molecular genetic comparisons between the lancelet and the vertebrates continue to shed light on the evolutionary origin of the vertebrates.
Publication: The amphioxus genome and the evolution of the chordate karyotype. Nature. 2008 June 19;453:1064-1071.