Paralytic shell fish poisoning is caused by

Options

A. Pinnularia
B. Gonyaulax
C. Elphidium
D. Vorticella.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the causative organism for Paralytic Shellfish Poisoning (PSP).

2. **Identifying the Organism**: We need to determine which of the given options (Pinularia, Goniolax, Alphidium, or Watticella) is responsible for causing this type of poisoning.

3. **Researching the Cause**: Paralytic shellfish poisoning is known to be caused by certain types of dinoflagellates. These are a group of single-celled organisms that can produce toxins.

4. **Identifying the Correct Dinoflagellate**: Among the options provided, Goniolax is identified as a dinoflagellate known to cause algal blooms that release toxins into the water.

5. **Understanding the Mechanism**: When dinoflagellates like Goniolax bloom, they release toxins into the water. Shellfish that filter feed on these dinoflagellates accumulate these toxins in their bodies.

6. **Effects on Humans**: When humans consume shellfish contaminated with these toxins, it leads to paralytic shellfish poisoning, which can cause severe neurological symptoms.

7. **Final Answer**: Therefore, the correct answer to the question is **Goniolax** (option B).

---