Grades K–2 · Organisms
How can a snail’s shell grow with the snail?
A snail’s shell is part of its body, not an empty house it borrows. A young snail already has a small shell. As the snail grows, its body can add more shell material.
In the diagramNew shell material joins the older shellolder shelladded rim
A soft body covering called the mantle makes the material for the shell. New material near the opening can make the shell larger. Material can also be added to make parts thicker.
The older shell stays joined to the newer part. Many snail shells therefore keep a curled shape as they grow. The snail carries the growing shell with it instead of moving into a new one.
About this explanation
Starting knowledge: Know that a snail has a soft body and a hard shell.
Sources
- Smithsonian National Museum of Natural History — Cowries: Mantle and Shell