Sea beans are a collective name for seeds and fruits that are dispersed by the sea. They come from trees and vines that grow alongside tropical streams, rivers and coasts all over the world. The seeds fall into waterways and travel to the ocean where they can float for thousands of kilometres on the ocean currents. Some will be washed up on beaches where they can germinate and grow.
This video shows a species of vine that produces the largest sea-pods in the world. Each pod contains a sea-bean which is carried by the ocean. It can be shown to students during a lesson on seed dispersal. Some questions to test their understanding are:

Why is it important that seeds are dispersed away from the parent plant?

So the offspring will grow away from the parent plant and each other, so there is no competition between them for resources such as water and light.

 

Other than water, what other methods of seed dispersal are there?

Wind, for example dandelion seeds. These are light enough to be carried on the wind.
Animals, seeds may be contained in a fruit which the animal eats. Some seeds have small hooks that attach themselves to animal fur.
Explosion, some seed pods can burst, projecting their seeds away from the parent plant.

Sea beans have an air pocket trapped inside. Why is this important?

So they are less dense than water so can float and reach beaches to germinate on.

Sea beans may reach the shores of the UK. Why don’t we have sea bean trees growing on our beaches?
It is not warm enough for germination to take place.

VIDEO: The Sea Bean

Related content
Students can investigate seed dispersal quantitatively by carrying out one of the ideas in Working Scientifically – Investigating seed dispersal.

By Gemma Young for Smart Learning