Final answer:
The statement is false; a heterocercal caudal fin has unequally sized lobes, with a larger upper lobe. When caudal lobes are similar in size, the fin is referred to as homocercal, not heterocercal.
Step-by-step explanation:
The statement that when the two caudal lobes are about the same size it is called heterocercal is false. In fact, a heterocercal caudal fin is characterized by unequally sized fin lobes, where the tail vertebrae extend into the larger upper lobe. This type of caudal fin is commonly found in Chondrichthyes, such as sharks and rays. When the two lobes of a caudal fin are approximately the same size, it is known as homocercal, not heterocercal, which is typically seen in bony fishes.
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