Question

A chordate character is

• A. gills
• B. spiracles
• C. post-anal tail
• D. chitinous exoskeleton.

Answer 1

The Correct Option is C

To determine which option is a chordate character, we need to understand the fundamental characteristics of chordates. The phylum Chordata is defined by the presence of the following key features at some stage of their development:

• Notochord: A flexible, rod-like structure that provides support.
• Dorsal hollow nerve cord: A tube-like structure that runs along the back of the animal, above the notochord.
• Pharyngeal slits: Openings in the pharynx that lead to the external environment. These may develop into gills in aquatic species.
• Post-anal tail: An extension of the body past the anal opening, used for locomotion in many aquatic species.

Now, let's analyze the given options:

1. Gills: While gills are present in many aquatic animals for respiration, they are not exclusively a chordate character. Many non-chordate aquatic organisms also have gills.
2. Spiracles: These are external respiratory openings found in some insects, arachnids, and some cartilaginous fish like sharks. Spiracles are not a characteristic feature of chordates.
3. Post-anal tail: This is a definitive characteristic of the chordates, present at least in the embryonic stage of all chordates.
4. Chitinous exoskeleton: This is characteristic of arthropods such as insects, not chordates. Chordates have an endoskeleton made of bone or cartilage.

Based on the characteristics outlined above, the post-anal tail is the correct answer because it is a distinguishing feature of the chordate phylum. This feature is used for locomotion and balance in many aquatic species and is present during some stage of development in all chordates.

Thus, the correct answer is post-anal tail.