Piles of sand you often see on the beach are commonly created by small creatures living beneath the surface.
The Creators: Lugworms
One of the primary reasons for distinct piles of sand, particularly the small, wiggly ones, is the activity of marine worms known as lugworms.
- Habitat: Lugworms live in burrows in the sand. These burrows can be found both on the beach itself and in the sandy seabed just offshore.
- Burrow Shape: Their burrows are typically u-shaped.
How Piles of Sand Are Formed
The process of creating these sand piles is part of the lugworm's feeding and respiration routine within its burrow.
- Swallowing Sand: A lugworm feeds by swallowing sand. This sand contains the organic matter and tiny organisms that the worm eats.
- Processing Sand: As the worm moves through its burrow and digests the edible material, it passes the sand through its body.
- Pooing It Out: The indigestible sand is then expelled, or 'pooed out', from one end of the burrow.
This expelled sand forms the characteristic pile on the surface of the beach near the entrance to the burrow.
What Are These Piles Called?
These wiggly piles of sand created by lugworms are specifically known as casts. They are a clear sign of a lugworm's presence underneath the sand.
Here's a simple overview:
| Creature | Action | Resulting Pile | Appearance |
|---|---|---|---|
| Lugworm | Swallows and expels sand | Casts | Wiggly, coiled pile |
In summary, the piles of sand you notice on the beach are often lugworm casts, formed when the lugworm processes sand from its burrow and pushes the waste material out onto the surface.
