Annelids develop embryonically as which type?

• A. Protostome
• B. Deuterostome
• C. Radial cleavage
• D. Spiral cleavage

Answer: (A)

Annelids are protostomes. In protostome development, the mouth forms from the blastopore first, and the anus develops later. Early cell divisions are typically spiral and determinate, and the coelom forms by schizocoely. This contrasts with deuterostomes, where the blastopore becomes the anus, cleavage is radial and indeterminate, and the coelom forms by enterocoely. Spiral cleavage is a hallmark of protostomes like annelids, but the key distinction here is that the developmental fate of the blastopore classifies them as protostomes.