The undifferentiated layer present between ectoderm and endoderm in diploblastic animals is known as:

Answer

To answer the question about the undifferentiated layer present between the ectoderm and endoderm in diploblastic animals, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Diploblastic Animals**:
- Diploblastic animals are organisms that develop from two primary germ layers during embryonic development: the ectoderm and the endoderm.

2. **Identify the Germ Layers**:
- The ectoderm is the outermost layer, while the endoderm is the innermost layer.

3. **Recognize the Layer Between Ectoderm and Endoderm**:
- In diploblastic organisms, there is an undifferentiated layer found between these two layers.

4. **Name the Undifferentiated Layer**:
- This undifferentiated layer is known as the mesoglea. It is gelatinous in nature and serves as an internal support structure.

5. **Functions of Mesoglea**:
- The mesoglea acts as an internal skeleton, providing support to the organism. It also aids in attachment and can play a role in the overall structure of the organism.

6. **Conclusion**:
- Therefore, the answer to the question is that the undifferentiated layer present between the ectoderm and endoderm in diploblastic animals is called **mesoglea**.