In which of the following caudal fin types is the posterior end of the vertebral column bent upward and continues up to the end of the caudal fin?

Correct option is D

→ In heterocercal caudal fins, the vertebral column bends upward and extends into the dorsal lobe of the tail.
→ The upper lobe is longer than the lower lobe, giving an asymmetrical appearance.
→ Common in primitive fishes like sharks and sturgeons.
Information Booster:
→ This fin type provides strong lift while swimming, compensating for the absence of swim bladders.
→ Helps fishes maintain depth and forward thrust simultaneously.
→ Evolutionarily significant trait seen in ancient fish groups.
Additional Information (Other Options):
(a) Hypocercal: Vertebral column bends downward.
(b) Homocercal: Symmetrical tail; vertebral column ends before fin.
(c) Gephyrocercal: Tail lost; fin replaced by continuous structure (e.g., Mola mola).