A) Herdmania
B) Balanoglossus
C) frog
D) fowl
Correct Answer: A
Solution :
In Herdmania, metamorphosis of the Ascidian larva is unique. It involves transformation of an active, free swimming larva with advanced characters such as axial notochord, dorsal neural tube and special sense organs, into an inert, sedentary and simple adult with only a pharynx with stigmata and endostyle to indicate its chordate nature. This type of metamorphosis which shows retrogression or degeneration from larva to adult is referred to as retrogressive metamorphosis. It is probably due to the sedentary mode of life of the adult. In contrast, the common type of metamorphosis in which a less developed larva changes into a more advanced adult is called progressive metamorphosis as seen in Balanoglossus, frog, fowl, etc.
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