Which of the following are categorized under Chordata ?

Options

A. Urochordata and cephalochordate
B. Hemichordata and urochordata
C. Craniata and Hemichordata
D. Vertebrata and Echinodermata

Answer

To determine which groups are categorized under Chordata, we need to analyze the characteristics that define this phylum. Here’s a step-by-step solution:

### Step 1: Understand the Key Characteristics of Chordata
Chordates are defined by three main characteristics:
1. **Notochord**: A flexible rod-like structure that provides support.
2. **Dorsal Nerve Cord**: A nerve cord that runs along the back of the organism.
3. **Pharyngeal Gill Slits**: Openings in the throat region that are involved in gas exchange.

### Step 2: Identify the Options Provided
The options given in the question are:
- Urochordata
- Cephalochordata
- Hemichordata
- Craniata
- Vertebrate
- Echinoderm

### Step 3: Analyze Each Option
1. **Urochordata**: This group possesses all three characteristics of Chordata (notochord, dorsal nerve cord, and pharyngeal gill slits). Therefore, it is categorized under Chordata.

2. **Cephalochordata**: Similar to Urochordata, this group also has all three defining characteristics of Chordata. Thus, it is also categorized under Chordata.

3. **Hemicordata**: This group has pharyngeal gill slits but lacks both the notochord and dorsal nerve cord. Therefore, it does not belong to Chordata.

4. **Craniata**: This group includes organisms with a skull and also possesses all three characteristics of Chordata. Hence, it is categorized under Chordata.

5. **Vertebrate**: Vertebrates are a subphylum of Chordata and possess all three characteristics, along with additional features like vertebrae. Thus, they belong to Chordata.

6. **Echinoderm**: Echinoderms are invertebrates and do not possess the defining characteristics of Chordata (specifically, they lack a dorsal nerve cord). Therefore, they are not categorized under Chordata.

### Step 4: Conclusion
Based on the analysis, the groups that are categorized under Chordata are:
- Urochordata
- Cephalochordata
- Craniata
- Vertebrate

### Final Answer
The correct options that are categorized under Chordata are **Urochordata, Cephalochordata, Craniata, and Vertebrate**.

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