List three similarities and dissimilarities between hemichordates and chordates.

Answer

### Step-by-Step Text Solution:

**Similarities between Hemichordates and Chordates:**

1. **Presence of Notochord:**
- Both hemichordates and chordates possess a notochord at some stage of their development. The notochord is a flexible rod-like structure that provides support.

2. **Presence of Gill Slits:**
- Both groups have gill slits at some point in their life cycle. These structures are involved in respiration and filter feeding.

3. **Dorsal Hollow Nerve Cord:**
- Both hemichordates and chordates have a dorsal hollow nerve cord. This nerve cord is located along the back of the organism and is involved in the nervous system.

**Dissimilarities between Hemichordates and Chordates:**

1. **Position of Gill Slits:**
- In hemichordates, the gill slits are positioned differently compared to chordates. In hemichordates, they are located in a more lateral position, while in chordates, they are typically arranged in a more ventral position.

2. **Length of Notochord:**
- The notochord in chordates is usually long and extends the length of the body, whereas in hemichordates, the notochord is short and does not extend the entire length of the body.

3. **Dorsal Hollow Nerve Cord Location:**
- In hemichordates, the dorsal hollow nerve cord is confined to the collar region only, while in chordates, the dorsal hollow nerve cord runs the length of the body.