Nematoda embryonic development is classified as which type?

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

Answer: (A)

Nematodes develop as protostomes, so their embryonic pattern centers on the blastopore forming the mouth. In protostomes, the initial opening becomes the mouth, and development is often determinate, with early cell divisions setting future fates in a fixed way. This contrasts with deuterostomes, where the blastopore typically becomes the anus and development follows a different cleavage pattern. While spiral cleavage is common among many protostomes, the key point for nematodes is that they follow the protostome mode of development, with the mouth arising early from the opening during gastrulation.