What is the main idea of the passage?

A mussel makes many strong, flexible threads that anchor it in moving water. (The passage explains how a mussel makes a bundle of byssal threads that bends, shares force, and can be renewed.)

Why is a bundle of threads useful in rough water?

Many threads can share pulls coming from different directions. (The text says many threads share the force and that rough water pulls in different directions, making a bundle more secure.)

What does “flexible” mean in this passage?

Able to bend without breaking (The threads bend while holding the mussel in place, so “flexible” means able to bend without breaking.)

What can a mussel do if one of its threads breaks?

Make a new thread (The second paragraph directly states that the animal can make a new thread when one breaks.)

How Mussels Hold On: Level 1 Reading Comprehension Questions

A mussel lives where moving water can pull hard. It cannot hold a rock with hands or claws. Instead, its foot places thin, sticky threads against the surface. These strong lines are called byssal threads. The mussel makes them from proteins and attaches them to the rock one by one.

One thread is small, but many threads share the force of a wave. Rough water pulls in different directions, so a bundle is safer than a single stiff link. The threads bend without letting the mussel drift away. If a thread breaks, the animal can make a new one. The mussel may also release old threads when it needs to move a short distance. This natural anchor is both firm and flexible. It shows how many light connections can do the work of one heavy chain.

Comprehension questions