Question

Locomotory organ of Annelida is
A. Sucker
B. Parapodia
C. Setae
D. All of the above

Answer 1

Hint: Annelids, as the name suggests (ring = ring), are segmented worms, and in most cases are externally recognized as ring contractions. Anatomical structures that help in the movement of animals like legs, wings, cilia, fins, and tail, are known as Locomotory structures.

Complete answer:
Let’s study each option one by one.
Parapodia: Most polychaetes walk on Parapodia. Under the action of segmentally Parapodia, they float on the water. During rowing, two Parapodia per segment are always in opposite phases of movement. Parapodia are hollow, segmented lateral extensions of the body usually divided into ventral neuropodia and dorsal notopodium. Each lobe has a tuft of hair, reinforced with a supporting acyclic. The point at which Parapodia is attached to the body wall acts as a hinge to move it back and forth. The cell cavity extends to the hydrostatic pressure exerted by the parapodia and the coelomic fluid.
Sucker-There are no Parapodia or setae in Hirudinea. Anchorage on the substratum while moving occurs due to two suckers. One is at the front (front of the frame) and the other is at the back of the body. The formation of suckers occurs by the fusion of many-body segments and they also play the role of adhesive organs. Adhesion occurs due to the presence of specialized sucker glands situated in the epidermis.
Setae-In oligochaetes, these movements are caused by setae, which are implanted directly into the muscles of the body and are mainly located in the central region of the body. There are different types of seats. It can be long or short, straight or curved, simple or branched pectin, or solid. In general, dense or long-branched cherries are typical for swimming in water. In buried species, setae are short and straight, simple and dull. Setae are produced and developed in a set of pouches. The stretching and pulling of the moving hand are caused by a pair of attached muscles and associated circular muscles.
So, we concluded that in Annelida locomotion occurs by all the above structures.
So, the correct answer is “Option D”.

Note:
Parapodia deform differently in different polychaetes. The change is related to various functions. They develop and modify into swimming and creeping types. With this form, Parapodia are localized in some anterior parts, for example, in the parietal part of the head, and are poorly developed or absent in other parts of the body. In sand burrowers, Parapodia are poorly developed or absent, especially in the back of the body.