Sand beach

They are wonderful

A mussel digging into the sand

Digging mussel
  1. With small light movements of the foot, the mussel makes a hole in the sand. Powerful movements would cause it to fly away because it is so light in the water.

  2. When the mussel has dug itself down a bit into the sand, it relaxes its adductor muscle and the two shell halves go apart so the surrounding sand is compressed and packed harder. The mussel is then well anchored for when it digs deeper with its foot. Excavation is made easier when water is squirted out of the shell casing around the foot.

  3. By pumping blood down to the foot it is able to function as an anchor. When the mussel constricts its foot, the lateral muscles pull the rest of the body downwards. This is made easier by small shell movements that cause trixotropi around them.
Try sticking different objects in the sand - in different ways - and in different types of bottoms. Try observing how different animals dig down into the sediment.

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Waves, bottoms and construction

Sand movement and erosion

Sand bottoms as living environments

The art of digging

Sand beach

Food web

Change and variation

Swedish beach life

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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson