''Branchiostoma floridae'', the Florida lancelet, is a

lancelet The lancelets ( or ), also known as amphioxi (singular: amphioxus ), consist of some 30 to 35 species of "fish-like" benthic filter feeding chordates in the order Amphioxiformes. They are the modern representatives of the subphylum Cephalochorda ...

of the genus ''

Branchiostoma ''Branchiostoma'' is one of the few living genera of lancelets ( order Amphioxiformes). It is the type genus of family Branchiostomatidae. These small vaguely eel- or snake-like animals are close relatives of vertebrates. The scientific name ...

''. The genome of this species has been sequenced, revealing that among the

chordate A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These fiv ...

s, the morphologically simpler

tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ca ...

s are actually more closely related to

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

s than lancelets. An embryo of a Florida amphioxus (''Branchiostoma floridae'') has a larval pharynx with gill slits that is asymmetrical. The gill slits in the larval pharynx form in the center of the embryo when it is in its earliest stage of development (primordial) meaning the thick layer of

endoderm Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gast ...

is overlapped by a thin layer; which aids into making the ''B. floridae'' asymmetrical from left to right. The lancelet Branchiostoma floridae maintains a high level of Fox transcription factor gene diversity, with 32 distinct Fox genes in its genome, and 21,229 clusters of cDNA clones, making it very useful to the research community.Yu, J., Wang, M., Shin-I, T., Kohara, Y., Holland, L. Z., Satoh, N., & Satou, Y. (2008). A cDNA resource for the cephalochordate amphioxus Branchiostoma Floridae. ''Development Genes and Evolution,'' ''218''(11-12), 723-727. doi:10.1007/s00427-008-0228-x

References

Cephalochordata {{chordate-stub