Why does earthworm always show cross-fertilzation ?

Explanation

**Step-by-Step Solution:**

1. **Understanding Earthworm's Reproductive System**: Earthworms are hermaphrodites, meaning they possess both male and female reproductive organs. This allows them to produce both sperm and eggs.

2. **Definition of Cross-Fertilization**: Cross-fertilization refers to the process where two different individuals exchange genetic material during reproduction, leading to fertilization of eggs by sperm from another organism.

3. **Protandrous Condition**: Earthworms exhibit a reproductive strategy known as protandry. In this condition, the male reproductive organs mature before the female reproductive organs. This means that when two earthworms come together, one will be ready to mate as a male before the other is ready to mate as a female.

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