Question

Which one of the following groups of animal is devoid of gill slits?

• A. Osteichthyes
• B. Cyclostomata and Chondrichthyes
• C. Echinodermata
• D. Adult Amphibians

Hint:

Pharyngeal gill slits are a hallmark of Chordates. To answer this question, you simply need to identify which group is not a chordate. Echinoderms (starfish, etc.) are a distinct invertebrate phylum.

Answer 1

The Correct Option is C

Step 1: Concept Overview:
A key characteristic of Chordata is the presence of pharyngeal gill slits at some point in their life cycle. We need to identify the group lacking this feature.
Step 2: Detailed Analysis:


Osteichthyes (Bony Fish): As chordates, they have gills covered by an operculum for respiration throughout life.

Cyclostomata (Jawless Fish) and Chondrichthyes (Cartilaginous Fish): These chordates possess exposed gill slits for respiration throughout their lives.

Echinodermata (e.g., Starfish, Sea Urchins): This invertebrate phylum lacks pharyngeal gill slits at all life stages, as they are not chordates. They respire using dermal branchiae (skin gills) or tube feet.

Adult Amphibians: Amphibians are chordates. While adults (e.g., frogs) develop lungs and lose gills, their larval tadpole stage has gills. Gill slits at any life stage define chordates.

Step 3: Final Conclusion:
Echinodermata is the only non-chordate group listed, thus lacking gill slits entirely.