Shells on the Beach

Lots of shells on the white sands.

The shells from this beach were lovely, lots of cockles, some really large.

Interestingly a lot of the shells were anchor points for seaweeds and bryozoans. This may indicate a sheltered area and the shells being relatively old.

This pinkish razor shell is a good example , and the shells below.

There are over two hundred species of cockle throughout the world. I was surprised by this. Cockles are bivalves , they have two parts to their shell and in the case of cockles they are the same size. Other bivalves can have different sized shells.

These above are Rough Cockles ( Anthocardia tuberculata) the common cockle (Cerastoderma edule) is very common and widespread.

Cockles live in the top few inches of sand and feed through their siphons filtering out plankton. They are quite mobile and can push themselves around with their ‘foot’.

Strong winds and storms can dislodge whole beds of cockles scattering them along a beach.

Below is a fossil cockle like bivalve I found in Dorset in the Greensand, it is almost identical to the modern shell above.

Other shells on this beach:-

The shell below is a pale Venus (Venus casina)

If you look carefully at some shells they have perfect hole in them . This has an interesting origin.

This is Venerupis decussata commonly called the cross cut carpet shell. It has a perfect small circular hole on the left.

This hole is drilled by a predatory Gastropod Natica . It feeds on the bivalve with its proboscis through the hole ! Interestingly this characteristic hole can also be found on fossil bivalves.

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