Which characteristic is shared by all deuterostomes?

• A. They undergo spiral cleavage during early development.
• B. They have radial symmetry as adults.
• C. They possess a chitinous exoskeleton.
• D. The blastopore develops into the anus during embryonic development.

Answer: (D)

Verified step by step guidance

1. Understand the term 'deuterostomes': Deuterostomes are a group of animals that share specific developmental characteristics during embryonic development.
2. Learn about the blastopore: In embryonic development, the blastopore is the opening that forms during gastrulation. In deuterostomes, the blastopore develops into the anus, which is a defining characteristic of this group.
3. Compare deuterostomes with protostomes: In protostomes, the blastopore develops into the mouth, whereas in deuterostomes, it develops into the anus. This distinction is key to understanding the difference between these two groups.
4. Clarify the incorrect options: Spiral cleavage is characteristic of protostomes, not deuterostomes. Radial symmetry as adults is seen in echinoderms (a subgroup of deuterostomes), but not all deuterostomes exhibit this trait. A chitinous exoskeleton is found in arthropods, which are protostomes, not deuterostomes.
5. Conclude with the correct characteristic: The defining feature of deuterostomes is that the blastopore develops into the anus during embryonic development, which sets them apart from other groups of animals.