In Hydra, absence of circulatory system is compensated by

Options

A. Gastrovascular cavity
B. Tentacles
C. Pseudocoelomic fluid
D. Mesoglea.

Answer

**Step-by-Step Solution:**

1. **Understanding Hydra's Anatomy**: Hydra is a simple organism belonging to the phylum Coelenterata (or Cnidaria). It has a body structure that includes a gastrovascular cavity, which is a central cavity involved in digestion and circulation.

2. **Identifying the Functions of the Gastrovascular Cavity**: The gastrovascular cavity serves two primary functions:
- **Digestion**: It helps in breaking down food.
- **Circulation**: It distributes nutrients throughout the body since Hydra lacks a specialized circulatory system.

3. **Evaluating the Options**:
- **Gastrovascular Cavity**: As explained, it plays a crucial role in both digestion and circulation in Hydra.
- **Tentacles**: These are used for capturing prey and do not serve a circulatory function.
- **Pseudocoelomic Fluid**: This term is not applicable to Hydra, which does not have a pseudocoelom.
- **Mesoglia**: This is a gelatinous substance present between the ectoderm and endoderm, but it does not perform circulatory functions.

4. **Conclusion**: Since the gastrovascular cavity is responsible for compensating for the absence of a circulatory system in Hydra, the correct answer is the gastrovascular cavity.

**Final Answer**: The absence of a circulatory system in Hydra is compensated by the gastrovascular cavity.

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