Common whelk ‘sea wash balls’ on the Guernsey shore

April 30th, 2013 by Richard Lord

A litter pick-up on the sea shore of Champ Rouget, on the path north of the Chouet tea rooms, Vale found eight ‘sea wash balls‘ from the common whelk, Buccinum undatum, three ray (rajidae) mermaid’s purses (egg case), and one cuttlebone from Sepia officinalis.

(click image to expand)

Eight ‘sea wash balls’ from whelks, three ray egg cases, and one cuttlebone were found during a beach clean on the sea shore at Champ Rouget, Chouet, Vale, Guernsey on 28 April 2013 (click image to expand)

A similar beach clean on the same stretch of shore on 17 February 2013 revealed only three mermaid’s purses and no whelk ‘sea wash balls’.

The common whelk, Buccinum undatum, usually lives on a sea floor of soft sediment. It is one of the larger marine snails in British waters.

Male and female whelks copulate between October and May depending on location in British Isle marine waters, and eggs are deposited in capsules that are glued together to form ‘sea wash balls’. These can be up to 50 cm by 25 cm in size.

‘Sea wash balls’ derive their name from their use by early mariners as a substitute for a sponge.

A ‘sea wash ball’ mass can contain as many as 2000 capsules, which may have been produced by more than one female, and each capsule can contain up to 1000 eggs, which are mostly food eggs, as usually only three to ten juvenile whelks emerge from each egg capsule after a development period that may be up to nine months.

The empty egg capsule masses are torn from their attachment and wash up on our shore where they can be found in the strand-line at this time of year.


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