Why do animals living in water usually have streamlined bodies?

Animals living in water have streamlined bodies because this shape helps them move smoothly and efficiently through water. A streamlined body reduces the resistance or drag created by water during movement.

Aquatic animals like fish need to swim quickly to find food, escape from predators, and move through their habitat. Their narrow, curved body shape allows water to flow around them easily, helping them travel faster while using less energy.

Along with streamlined bodies, many aquatic animals have fins and tails that help them control direction, maintain balance, and swim effectively. These features are adaptations that allow water-living organisms to survive successfully in their aquatic environment.