In this article we will discuss about the structure of Chaetopterus with the help of a diagram.
1. They are marine, tubicolous and burrowing worms.
2. The tubes are “U” shaped and are lined with thick mucous secreted by the animal.
3. Body is about 20—30 cm in length and is divisible into an anterior, a middle and a posterior region.
4. The anterior region is comprised of 15 segments, the middle region of 3 segments and the posterior region of about 30 segments.
5. The prostomium and peristomium are reduced and tentacles and palps are absent.
6. Mouth is surrounded by funnel like peristomial collar.
7. A pair of backwardly directed peristomial cirri are present on peristomual collar. Pharynx Is non-protusible.
8. All anterior segments bear parapodia with large notopodia.
9. The first segment of middle region bears a pair of great “wings” which are modified notopodium. Segments 1-15 bear five suckers which are also modified notopodia. The segments 13 to 15 bear flat and large fans (the modified notopodia).
10. The segments in posterior region are all alike and bear biramus parapodia. They are devoid of gills or branchiae.
11. Water currents are maintained by flapping of fans and the food particles are trapped by mucus secreted by anterior region and are converted into a. ball inside the food-cup. The ball from here Is pushed forward to the mouth along a dorsal groove.
12. Exhibits luminescence and emits blue green light.