List four effects of light on animals.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Source of Light**: The primary source of light for animals is the sun. This natural light influences various biological processes in animals.

2. **Effect 1 - Color Vision**: Light is essential for animals to perceive colors. The presence of light allows animals to see and differentiate between various colors, which is crucial for their survival, such as finding food or avoiding predators.

3. **Effect 2 - Photoperiodic Biological Rhythms**: Many animals rely on light to regulate their biological rhythms. These rhythms include sleep-wake cycles and seasonal behaviors, which are influenced by the length of day and night (photoperiod). This helps in synchronizing their activities like feeding and mating with environmental changes.

...