Question

Which one of the following is a larval form of jelly fish?

• A. Amphiblastula
• B. Ephyra
• C. Redia
• D. Rhabditiform

Hint:

Associate key larval forms with their phyla:

\textbf{Cnidaria (Jellyfish):} Planula, Ephyra
\textbf{Porifera (Sponges):} Parenchymula, Amphiblastula
\textbf{Platyhelminthes (Flukes):} Miracidium, Sporocyst, Redia, Cercaria
\textbf{Nematoda (Roundworms):} Rhabditiform, Filariform \end{itemize} Knowing these associations is very helpful for matching-type questions.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This question requires knowledge of the life cycles of various invertebrates to identify the larva specific to jellyfish (Phylum Cnidaria, Class Scyphozoa).

Step 2: Detailed Explanation of Options:
- Amphiblastula: This is a free-swimming larval stage of certain sponges (Phylum Porifera).
- Ephyra: This is a juvenile, free-swimming medusa stage of a jellyfish. It is produced asexually by the budding (strobilation) of a polyp stage called a scyphistoma. The ephyra matures into the adult jellyfish.
- Redia: This is a larval stage in the life cycle of flukes (Phylum Platyhelminthes, Class Trematoda), which develops within a snail host.
- Rhabditiform: This is the name given to the first-stage larva of many nematodes (Phylum Nematoda), such as hookworms and roundworms.

Step 3: Final Answer:
Based on the analysis, the ephyra is the correct larval/juvenile form associated with the jellyfish life cycle. Therefore, option (B) is the correct answer.