Question:
Type of caudal fin present in classes Dipnoi and Holocephali is
Type of caudal fin present in classes Dipnoi and Holocephali is
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The prefix "di-" in diphycercal hints at the symmetrical division of the fin lobes with the vertebral column extending straight down the center.
Updated On: Jul 9, 2026
- Protocercal
- Homocercal
- Diphycercal
- Isocercal
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
Caudal fins in fish are categorized based on their symmetry and structural support.
A diphycercal tail is symmetrical both externally and internally, with the vertebral column extending straight to the tip, dividing the fin into equal dorsal and ventral lobes.
Step 2: Detailed Explanation:
- Protocercal: The primitive, simple tail where the vertebral column extends straight to the tip, and the fin is a simple fold (seen in larval fish and cyclostomes).
- Heterocercal: An asymmetrical tail where the vertebral column bends upward into the larger dorsal lobe (seen in sharks).
- Homocercal: Symmetrical externally but asymmetrical internally, supported by hypural bones (seen in teleosts).
- Diphycercal: Symmetrical externally and internally, with the vertebral column extending straight to the end of the tail (seen in lungfishes (Dipnoi) and chimaeras (Holocephali)).
In lungfishes and chimaeras, the caudal fin has evolved into a symmetrical, tapering structure.
Step 3: Final Answer:
Thus, a diphycercal caudal fin is present in the classes Dipnoi and Holocephali.
Caudal fins in fish are categorized based on their symmetry and structural support.
A diphycercal tail is symmetrical both externally and internally, with the vertebral column extending straight to the tip, dividing the fin into equal dorsal and ventral lobes.
Step 2: Detailed Explanation:
- Protocercal: The primitive, simple tail where the vertebral column extends straight to the tip, and the fin is a simple fold (seen in larval fish and cyclostomes).
- Heterocercal: An asymmetrical tail where the vertebral column bends upward into the larger dorsal lobe (seen in sharks).
- Homocercal: Symmetrical externally but asymmetrical internally, supported by hypural bones (seen in teleosts).
- Diphycercal: Symmetrical externally and internally, with the vertebral column extending straight to the end of the tail (seen in lungfishes (Dipnoi) and chimaeras (Holocephali)).
In lungfishes and chimaeras, the caudal fin has evolved into a symmetrical, tapering structure.
Step 3: Final Answer:
Thus, a diphycercal caudal fin is present in the classes Dipnoi and Holocephali.
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