Blind sac body plan is found in

Options

A. Sponges
B. Annelids
C. Coelentrates
D. Round worms

Answer

To determine which group of animals exhibits a blind sac body plan, we can analyze each option provided in the question:

1. **Sponges**:
- Sponges belong to the phylum Porifera. They do not have a true body plan like the others mentioned. Instead, they have a cell aggregate plan where cells are loosely organized and perform various functions. Therefore, sponges do not exhibit a blind sac body plan.

2. **Annelids**:
- Annelids are segmented worms that belong to the phylum Annelida. They possess a tube within a tube body plan, meaning they have both a mouth and an anus. This structure allows for a complete digestive system. Thus, annelids do not have a blind sac body plan.

3. **Cnidarians**:
- Cnidarians, which include jellyfish, corals, and sea anemones, have a body plan that can be described as a blind sac. They possess a single opening that serves both as a mouth for food intake and an anus for waste expulsion. This characteristic defines their blind sac body plan.

4. **Roundworms**:
- Roundworms belong to the phylum Nematoda. They also have a tube within a tube body plan, featuring both a mouth and an anus, similar to annelids. Therefore, roundworms do not exhibit a blind sac body plan.

Based on the analysis, the correct answer to the question "Blind sac body plan is found in" is:

**C. Cnidarians**