Question

Metamorphism of Ascidia is known as
A) Holometabolous
B) Paurometabolous
C) Hemimetabolous
D) Retrogressive metamorphosis

Answer 1

The amphibians like tadpole and other organisms undergo a metamorphosis process that includes the stages the organisms go through from larva to an active adult. Different organisms possess different metamorphosis processes.

Complete answer:
To answer this question, we have to know details about metamorphosis. The metamorphosis is meant by form; it is the change in the minerals assemblage and texture that results in the change in the structure from larva to an adult. The metamorphism of tadpole larvae undergoes different changes in the shape to form sessile adults.
Now, during metamorphism of ascidians swimming larvae attach to the substances and start the change in structure to form feeder adults. All the ascidian are lecithotrophic, they produce adhesives through the epidermis of the trunk retraction, and eversion of the papillae, then regression of the tails occurs that results in loss of outer layer of the larval tunic, then expansion and elongation of zooids in juveniles takes place and also the reciprocation of ampullae, reorientation of vesicles, and tunic expansion takes place. The Ascidia metamorphism is known as retrogressive metamorphism. In the retrogressive metamorphism, the larva consists of advanced characteristics that get lost during the development. The adult is sedentary with the primitive characters. The progressive and active larva metamorphoses into sedentary and retrograde bag-like organisms. The adults remain bound to the rocky substratum throughout their life and use the water current to pass through the perforated pharynx that they also used for microorganisms used for feed.

Thus, the correct option is ‘D’ Retrogressive metamorphism.

Note: The holometabolous is the development of insects that undergo complete metamorphosis from the immature stage that is larva. In this type of metamorphism the transformation of an adult from larva takes place during the resting stage of the pupa.