What Embryonic Structures are Common in All Chordates

Question

What embryonic structures are common in all chordates?
A) pharyngeal slits
B) arrector pili
C) gametophytes
D) vertebrae

Accepted Answer

Pharyngeal slits are a feature of all chordate embryos, although they may be modified or lost in adult forms. These slits function to filter food particles from the water in aquatic forms, or to provide gas exchange in some terrestrial forms, and eventually give rise to gill arches and other structures. Arrector pili are small muscles associated with hair follicles and are not a characteristic of chordates. Gametophytes are the haploid generation of plants, and are not present in animals. Vertebrae are only present in vertebrate chordates, whereas other chordates have notochords or other structures that provide support.