At some point in life every chordate has gill slits, but when do zebras have gill slits?

answer:

a chordate is an animal of the phylum chordata. during some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle,: these five anatomical features define this phylum. chordates are also bilaterally symmetric; and have a coelom, metameric all chordates are coelomates, and have a fluid filled body

explanation:

answer; i believe the answer is hydraulic action;