Pseudocoel occurs in

Options

A. Hydra
B. Ascaris
C. Cockroach
D. Earthworm

Answer

To determine where pseudocoel occurs, we need to analyze the options provided and understand the concept of pseudocoelom.

### Step-by-Step Solution:

1. **Understanding Pseudocoelom**:
- A pseudocoelom is a type of body cavity that is not completely lined by mesoderm. It is a space between the body wall and the gut wall, which is partially lined by mesodermal tissue.

2. **Identifying the Organisms**:
- The options given are Hydra, Ascaris, Cockroach, and Earthworm.

3. **Analyzing Each Option**:
- **Hydra**:
- Hydra belongs to the phylum Cnidaria. These organisms are diploblastic, meaning they have only two germ layers (ectoderm and endoderm) and lack a mesoderm. Therefore, they do not have any body cavity, including pseudocoelom.

- **Ascaris**:
- Ascaris is a roundworm that belongs to the phylum Aschelminthes (or Nematoda). This organism possesses a pseudocoelom, which is a characteristic feature of this phylum. The mesoderm in Ascaris is present only in the form of pouches around the gut.

- **Cockroach**:
- Cockroaches belong to the phylum Arthropoda. They possess a true coelom known as a hemocoel, which is filled with hemolymph. Therefore, they do not have a pseudocoelom.

- **Earthworm**:
- Earthworms belong to the phylum Annelida. They have a true coelom, which is a fully lined body cavity, and thus do not have a pseudocoelom.

4. **Conclusion**:
- After analyzing all the options, the only organism that possesses a pseudocoelom is **Ascaris**.

### Final Answer:
Pseudocoel occurs in **Ascaris**.

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