Differentiate between Haemocoel and true coelom

Explanation

### Step-by-Step Solution

1. **Definition of Haemocoel**:
- Haemocoel is the primary body cavity found in certain invertebrates. It is also referred to as the blastocoel. This cavity is filled with hemolymph, which serves as a circulatory fluid.

2. **Definition of True Coelom**:
- True coelom, also known as eucoelom, is a secondary body cavity that is fully lined with mesodermal tissue. It is found in more complex organisms and allows for the development of more sophisticated organ systems.

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