V: Smaller Coelomate Groups--Chaetognatha, Hemichordata
, Pogonophora, Phoronida, Ectoprocta, Brachiopoda, Sipunculida.
He said these tubes are the missing link connecting the two main hemichordata
groups, which also included the now-extinct graptolites.
Molecular phylogeny of hemichordata
, with updated status of deep-sea enteropneusts.
Here we present a molecular phylogeny of Hemichordata
that includes novel sequence data from 35 taxa representing all hemichordate families, at least 12 of which are distinct genetic lineages not attributable to known species.
The phylum Hemichordata
is divided into two classes: Pterobranchia and Enteropneusta.
A parallel situation exists for the phylum Hemichordata
, wherein enteropneusts form their coeloms largely by enterocoely, but pterobranchs do so by schizocoely (Lester, 1988); however, an evolutionary explanation of the difference is hampered by current uncertainty as to whether pterobranchs are basal or derived within the phylum (Sato et al.
221-347 in Microscopical Anatomy of Invertebrates: Hemichordata
, Chaetognatha and the Invertebrate Chordates, Vol.
, Chaetognatha, and the Invertebrate Chordates, G.
The deuterostome phylum Hemichordata
is composed of three extant classes: the Enteropneusta are solitary worms, the Pterobranchia are colonial tube-dwelling suspension feeders, and the Planktosphaeroidea are known only from their larvae.