The
correct answer is pharyngeal pouches.
All
chordates for at least some period of their life have pharyngeal pouches (pharyngeal
slits). Those are the openings in the pharynx with the function in the
filter-feeding. Pharyngeal slits are present during the embryonic stages of
tetrapod development. They develop into gill arches (bony fish) and into the jaw and inner ear (terrestrial
animals).
