Read the characteristics given below of a chordate:
a) two-chambered heart
b) poikilotherms
c) exclusively marine
e) oviparous with direct development
e) separate sexes
Which of the following possess all of the above features?

Options

A. Labeo
B. Rana
C. Trygon
D. Exocoetus

Answer

To solve the question regarding the characteristics of a chordate, let's analyze each characteristic step by step:

### Step 1: Identify the Characteristics
The characteristics given are:
1. Two-chambered heart
2. Poikilotherms (cold-blooded)
3. Exclusively marine
4. Oviparous with direct development
5. Separate sexes

### Step 2: Understand Each Characteristic
- **Two-chambered heart**: This type of heart is found in fish, consisting of one atrium and one ventricle.
- **Poikilotherms**: These are organisms that cannot regulate their body temperature internally, meaning their body temperature varies with the environment. Most fish fall into this category.
- **Exclusively marine**: This indicates that the organism lives only in saltwater environments.
- **Oviparous with direct development**: Oviparous means that the organism lays eggs, and direct development means that the young hatch from eggs and resemble adults without undergoing a larval stage.
- **Separate sexes**: This means that there are distinct male and female individuals.

### Step 3: Evaluate Each Option
Now, let's evaluate the options provided in the question:
1. **Lebu (Labeo)**: This is a freshwater fish, so it does not meet the "exclusively marine" criterion.
2. **Rana (Frog)**: Frogs are amphibians, not fish, and they do not have a two-chambered heart (they have three). They also do not fit the exclusively marine requirement.
3. **Stingray**: While stingrays are marine, they do not have a two-chambered heart; they have a more complex circulatory system.
4. **Exocetus (Flying Fish)**: This fish possesses a two-chambered heart, is poikilothermic, is exclusively marine, is oviparous with direct development, and has separate sexes.

### Step 4: Conclusion
Based on the analysis, the only organism that possesses all the given characteristics is **Exocetus (Flying Fish)**.

### Final Answer
**The correct answer is Exocetus (option 4).**

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