How Seaweed Holds On and Drinks

In the picture

1. 1Holdfast: the knotted base that grips the rock like a claw.
2. 2Blade: the flat part that soaks up water and minerals all over.
3. 3Oak roots: they pull water and minerals up from the soil.

Examples

• Kelp on a rocky shore stays in place during storms because its holdfast grips the stone.
• A sponge dropped in a bowl of water soaks it up on every side, a bit like a seaweed blade.

Quiz: How Seaweed Holds On and Drinks (Age 10)

1. 1

   What is the main job of a seaweed’s holdfast?

   • To soak up water and minerals from the rock
   • To grip the rock so the seaweed stays in place
   • To store food for the seaweed
2. 2

   How does seaweed take in water and minerals?

   • Through roots that grow into cracks in the rock
   • Through its holdfast, like a straw
   • Through its whole surface, all over
3. 3

   How is an oak tree different from seaweed when it comes to getting water and minerals?

   • The oak takes them in through its roots, while seaweed soaks them up all over
   • The oak soaks them up through its leaves, while seaweed uses its holdfast
   • They both use roots, but seaweed’s roots are much shorter

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.