Question

The gill-slits of chordates occur in:

• A. Buccal cavity of aquatic animals
• B. Pharynx of all land vertebrates
• C. Pharynx of all chordates' embryos and pharynx of aquatic adult chordates
• D. Pharynx of all aquatic and land vertebrates in adults as well as in their embryos

Answer 1

The correct option is C Pharynx of all chordates' embryos and pharynx of aquatic adult chordates

Gill slits are individual openings to gills, which include multiple gill arches and lack a single outer cover. These can be traced in cartilaginous fish, such as shark and rays. Early embryos of different vertebrates resemble each other in possessing certain similar structures, like the gill slits. Therefore, gill slits of chordates occur in the pharynx of all chordates' embryos and the pharynx of some aquatic adult chordates.