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: Understanding the Concept:
The presence of pharyngeal gill slits at some stage of life is one of the defining characteristics of the phylum Chordata. The question asks to identify the group of animals that does not possess this feature.
Step 2: Detailed Explanation:


Osteichthyes (Bony fish): These are chordates and possess gills covered by an operculum throughout their lives for respiration.

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

Echinodermata (e.g., starfish, sea urchins): This is a phylum of marine invertebrates. They are not chordates and therefore completely lack pharyngeal gill slits at all stages of their life. They typically respire using dermal branchiae (skin gills) or tube feet.

Adult Amphibians: Amphibians are chordates. While the adult forms (like frogs) typically lose their gills and develop lungs for respiration, their larval stage (tadpole) possesses gills. The presence of gill slits at some point in the life cycle is a chordate feature.

Step 3: Final Answer:
Echinodermata is the only group listed that is not in the phylum Chordata and is therefore completely devoid of gill slits.