Which embryonic development pattern do chordates show?

• A. Protostome
• B. Deuterostome
• C. Lophotrochozoan
• D. Ecdysozoan

Answer: (B)

Chordates develop as deuterostomes, a pattern in which the blastopore becomes the anus and the mouth forms later from a second opening. This development is usually accompanied by radial, indeterminate cleavage and coelom formation by enterocoely, features shared with other deuterostomes like echinoderms. This distinguishes them from protostomes, where the blastopore typically becomes the mouth. The terms lophotrochozoan and ecdysozoan refer to large animal groups defined by broader developmental and morphological traits, not the specific embryonic opening fate, so they don’t describe how chordate embryos develop.