Grades K–2 · Organisms
How can a pufferfish make its body bigger?
A pufferfish can change from a small-looking fish into a much rounder one. It does not grow a new body in a few moments. It takes water into a space inside its body.
In the diagramPumped water changes a fish’s shape▸ Ordinary shapeExpandable bodyStomachWater inInflation is not rapid tissue growth.
Its mouth area works as a pump. Muscles move this area to draw in water and send it toward the stomach. The stomach can stretch and hold the extra water.
The filled stomach pushes the body outward. This bigger shape can make the fish harder for a predator to swallow. It is a temporary change, not the same as growing bigger over time.
About this explanation
Starting knowledge: Understands that adding water to an expandable space can change its size.
Sources
- Smithsonian Institution — Pufferfishes and Their Relatives
- Wang and colleagues, Integrative Zoology — Neural basis of the stress response in a pufferfish, Takifugu obscurus