Limpets are useful as bait for fish. The Whelk and Periwinkle are gathered in immense numbers, and are used by us for food. Perhaps you have seen the egg-bundle of the Whelk. It contains many eggs when first laid in the sea. Each egg is as big as a pin's head. They swell in the water, until the yellowish bundle is three times as large as the Whelk that laid it. You often see the empty bundle blown by the wind along the shore.
EXERCISES
1. Give the names of two bi-valve molluscs.
2. What is the Periwinkle's shell made of?
3. Describe how the Periwinkle eats seaweed.
4. How does the Whelk obtain its food?
5. Give the names of three one-shelled molluscs.