Select the Taxon mentioned that represents both marine and fresh water species

Options

A. Echinoderms
B. Ctenophora
C. Cephalochordata
D. Cnidaria

Answer

To solve the question of which taxon represents both marine and freshwater species, we can follow these steps:

### Step 1: Understand the Taxa
We have four options to consider:
- A. Echinoderms
- B. Cephalocordata
- C. Ctenophora
- D. Cnidaria

### Step 2: Analyze Each Taxon
- **Echinoderms**: This group includes starfish, sea urchins, and sea cucumbers, which are exclusively marine species. Therefore, they do not represent freshwater species.

- **Cephalocordata**: This group, which includes lancelets, is also exclusively marine. Thus, it does not represent freshwater species.

- **Ctenophora**: This group includes comb jellies, which are primarily marine organisms. They do not include freshwater species.

- **Cnidaria**: This group includes jellyfish, corals, and sea anemones. While many cnidarians are marine, some species (like certain hydras) can be found in freshwater environments.

### Step 3: Conclusion
Based on the analysis, the only taxon that includes both marine and freshwater species is **Cnidaria**. Therefore, the correct answer is:

**Option D: Cnidaria**