Question

What are the 3 classes of Annelida?

Answer 1

Annelida:

1. Annelida is the phylum that comprises segmented worms.
2. These species can be found in a variety of settings, including marine, terrestrial, and freshwater, but the presence of water or humidity is essential for their survival, especially in terrestrial areas.
3. Annelids are triploblastic and coelomate, organized at the organ system level, bodies are divided into sections, breath via the surface of their bodies, excretory organs are known as nephridia, and circulatory and digestive systems are well-developed.
4. Three classes of annelids: Polychaeta, Oligochaeta, Hirudinea

Polychaeta:

1. The body is separated into parts and is elongated and can only be found in the ocean.
2. Their neurological system is well-developed, and their circulatory system is closed and is bilaterally symmetrical.
3. Metanephridia and protonephridia are the mechanisms through which they excrete. Fertilization occurs outside of the body.
4. For example, Nereis and Syllis

Oligochaeta:

1. Freshwater and terrestrial creatures make up the majority of them.
2. They are hermaphrodites, yet they do cross-fertilize.
3. Fertilization occurs outside of the body, and there is the production of cocoons.
4. Setae are divided into segments.
5. They don't have parapodia, but they do have clitellum.
6. Monoecious creatures are included in this category.
7. They do not have a free larval stage, and their development takes place entirely within the cocoons.
8. For example, Pheretima and Tubifex

Hirudinea:

1. Freshwater is the most prevalent habitat.
2. Some are parasitic, marine, or terrestrial.
3. There are no tentacles, parapodia, or setae to be found.
4. The body is flattened dorsoventrally or cylindrically.
5. On the ventral side, they feature an anterior and posterior sucker.
6. Cocoons are where the creatures deposit their eggs.
7. During the development of the organism, there is no larval stage.
8. Internal fertilization occurs.
9. They are hermaphrodites.
10. Hirudinaria is an example