Question

Retrogressive metamorphosis occurs in ____________ .
A. Hemichordata
B. Cephalochordata
C. Urochordata
D. Vertebrata

Answer 1

Hint: The hatching has advanced characters that are lost during the turn of events in a retrogressive transformation and the adult has either inactive or coarse characters that deteriorate. Transformation is a transition from the adolescent phase to the adult phase, where the larval phase is not the same as the adult phase.

Complete answer:
Retrogressive metamorphosis takes place in Urochordates. In retrogressive transition, the hatching continued to inherit characters that were lost during the turn of events, and the adult was either inactive or degraded with crude characters. Urochordata adults exhibit inactive degenerative characters, while free-swimming fledgling hatchlings show advanced characters of chordate that are lost during transformation. Parasitic scavengers, such as Sacculina, Copepod parasites, stylopids, and scale bugs (Insects) also show a retrogressive transformation.
There is a bar like a notochord in the tail to which swimming muscles are attached. There is an empty dorsal nerve rope, which is enlarged to form the head at the front end. The statocyst is linked to the other side as a photoreceptor and an adaptive heart. The pharynx has only two sets of gill slits, but the mouth is covered with a film and the digestive tract is simple. Endostyle has evolved a lot on the ventral side of the pharynx. The heart is on the ventral side of the intestine, so it is not useful. The hatchling has three ectodermal papillae at the front end, which support the strong connection to the base of the body

Therefore, the right answer is 'Urochordata.'

Note: Herdmania's fledgling hatchling is just 1-2 mm long when the egg is incubated. It has only 3 hours of endurance during which it needs to swim in search of a reasonable link base. The hatchling requires advanced highlights for its free-swimming appearance, which is so important for the dispersal of the population to inaccessible spots that the stationary adult has no way to do.