Researchers have provided new insight into the life history strategies of the two main clades of ‘enteropneusts,’ which are benthic marine invertebrates belonging to the deuterostome phylum Hemichordata. One clade, which includes Spengelidae and Ptychoderidae, shows indirect development via a larval stage. The other clade, Harrimanidae, does not have a larval stage during its development. Previous molecular studies on the adult body plans of enteropneusts have focused on a member of the Harrimanidae. The new study examines a member of Spengelidae, allowing comparison between the two developmental strategies. The study could help to address long standing questions about the evolution of developmental strategies, as well as the evolution of metazoan larval forms.

The study, “The development and metamorphosis of the indirect developing acorn worm Schizocardium californicum (Enteropneusta: Spengelidae),” was published in the journal Frontiers in Zoology. The work was supported by NASA Astrobiology through the Exobiology Program.