Why do fish open and close their mouths?

Why do fish open and close their mouths?

Fish open and close their mouths to pump water across their gills. This allows them to extract oxygen from the water for respiration. Some also do it to filter feed or capture prey.

Why It Matters

This fact belongs to the general category and contributes to expanding general knowledge. Understanding such facts not only makes you smarter but also helps connect ideas across different fields.

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