Animals of colder regions and fishes of cold water have thicker layer of subcutaneous fat. Describe why?

Explanation

### Step-by-Step Solution:

1. **Understanding the Context**: The question refers to animals living in colder regions and cold-water fishes, which have a thicker layer of subcutaneous fat. This adaptation is crucial for their survival in extreme cold.

2. **Identifying the Tissue**: The layer of fat mentioned is primarily composed of adipose tissue, which is a type of connective tissue found in animals.

3. **Function of Adipose Tissue**: Adipose tissue serves multiple functions:
- It acts as a fat-storing tissue, providing energy reserves.
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