Which one of the following statements about all the four of Spongilla, leech, dophin and penguin is correct ?

Options

A. Spongilla has special collared cells called choanocytes, not found in the remaining three.
B. Penguin is homoeothermic, while the remaining three are poikilothermic
C. Leech is a freshwater form, while all other are marine.
D. All are bilaterally symmetrical.

Answer

To determine which statement is correct about Spongilla, leech, dolphin, and penguin, we need to analyze the characteristics of each organism.

### Step 1: Identify the Organisms and Their Classifications
- **Spongilla**: This is a type of sponge belonging to the phylum **Porifera**.
- **Leech**: This is a segmented worm belonging to the phylum **Annelida**.
- **Dolphin**: This is a marine mammal belonging to the class **Mammalia**.
- **Penguin**: This is a flightless bird belonging to the class **Aves**.

### Step 2: Analyze Each Statement
1. **Statement 1**: "Spongilla has specialized collared cells (choanocytes) and these are not found in the remaining three."
- **Analysis**: Sponges possess choanocytes, which are specialized cells that help in feeding. Leeches, dolphins, and penguins do not have these cells. This statement is **correct**.

2. **Statement 2**: "Penguin is homeothermic and the remaining three are poikilothermic."
- **Analysis**: Penguins are indeed homeothermic (warm-blooded), but dolphins are also homeothermic. Therefore, this statement is **incorrect**.

3. **Statement 3**: "Leech is a freshwater form while all others are marine."
- **Analysis**: Leeches are primarily found in freshwater, while dolphins and penguins are marine animals. However, Spongilla can also be found in freshwater. Thus, this statement is **incorrect**.

4. **Statement 4**: "All are bilaterally symmetrical."
- **Analysis**: Leeches, dolphins, and penguins are bilaterally symmetrical. However, Spongilla is asymmetrical or exhibits radial symmetry. Therefore, this statement is **incorrect**.

### Conclusion
After analyzing all the statements, the only correct statement is the first one: "Spongilla has specialized collared cells (choanocytes) and these are not found in the remaining three."

### Final Answer
The correct statement about all four organisms is: **Spongilla has specialized collared cells (choanocytes) and these are not found in the remaining three.**

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