Which of the following are referred as non-vertebrate chordate?

Options

A. Ciona, Ascidia, Amphioxus
B. Lamprey,Myxine, Shark
C. Scoliodon, Torpedo, Trygon
D. Pristis, branchiostoma, Scyllium

Answer

To determine which of the following are referred to as non-vertebrate chordates, we need to analyze the options provided and understand the classification of chordates.

### Step-by-Step Solution:

1. **Understand Chordate Classification**:
- The phylum Chordata is divided into two main subphyla:
- **Vertebrata** (vertebrates) which have a backbone.
- **Protocordata** (non-vertebrate chordates) which do not have a backbone.

2. **Identify Protocordata Groups**:
- Protocordata is further divided into two groups:
- **Tunicata (Urochordata)**: These are marine animals that have a notochord only in the larval stage.
- **Cephalocordata**: These are small, fish-like animals that retain the notochord throughout their life.

3. **List the Options**:
- The options provided are: Siona, Ascidia, Amphioxus, Lamprey, Myxine, Shark, Scoliodon, Torpedo, Trigon, Pristis, Brachistoma, and Silium.

4. **Classify Each Option**:
- **Siona**: A tunicate (Urochordata) - Non-vertebrate.
- **Ascidia**: A tunicate (Urochordata) - Non-vertebrate.
- **Amphioxus**: A cephalocordate - Non-vertebrate.
- **Lamprey**: A cyclostome (vertebrate) - Vertebrate.
- **Myxine**: A cyclostome (vertebrate) - Vertebrate.
- **Shark**: A cartilaginous fish (vertebrate) - Vertebrate.
- **Scoliodon**: A dogfish (vertebrate) - Vertebrate.
- **Torpedo**: A cartilaginous fish (vertebrate) - Vertebrate.
- **Trigon**: A cartilaginous fish (vertebrate) - Vertebrate.
- **Pristis**: A houndfish (vertebrate) - Vertebrate.
- **Brachistoma**: A cephalocordate - Non-vertebrate.
- **Silium**: This option is unclear but does not typically refer to a known chordate.

5. **Identify Non-Vertebrate Chordates**:
- From the above classifications, the non-vertebrate chordates are:
- Siona
- Ascidia
- Amphioxus
- Brachistoma

### Final Answer:
The non-vertebrate chordates from the options provided are **Siona, Ascidia, Amphioxus, and Brachistoma**.