For 10 points, name this phylum whose notochord-possessing members include the vertebrates.
Certain members of this phylum mate with males of a related species and discard their sperm after fertilization in a process known as hybridogenesis, while some unisexual members of the same class cryptically steal heterospecific sperm through kleptogenesis. Basal members of one clade in this phylum eat their way out of deep-sea carcasses and have caudal hearts. Though initially placed in this phylum, acorn worms were later reclassified into a related (*) "hemi" phylum. Distinguishing features of this phylum include a post-anal tail, pharyngeal slits, and a dorsal nerve chord. This deuterostome phylum contains lancelets, tunicates and craniates. For 10 points, name this phylum whose notochord-possessing members include the vertebrates.
Certain members of this phylum mate with males of a related species and discard their sperm after fertilization in a process known as hybridogenesis, while some unisexual members of the same class cryptically steal heterospecific sperm through kleptogenesis.
Chordata [or Chordates]